Slav Gambit:

Early Alternatives

A game that I liked (ChessBase 13)
[Event "3...c6 Triangle System, Slav gambit"] [Site "?"] [Date "????.??.??"] [Round "?"] [White "Queen's Gambit Declined"] [Black "?"] [Result "*"] [ECO "D31"] [Annotator "kestenberg,tal"] [PlyCount "15"] 1. d4 d5 2. c4 e6 3. Nc3 c6 {The Triangle System} 4. e4 {A principled move, black allows white's pawn in the center and white takes the oppertunity, however this does involve a pawn sacrifice.} dxe4 5. Nxe4 Bb4+ $5 {this tactical detail forces white to part with a pawn to fight for advantage} 6. Bd2 $5 {The active way to block the check, but in the process of developing white blocks the queen's defense of the d pawn} (6. Nc3 {is rather toothless dispite its recent use in a WCH match, black equalizes with a quick central break} c5 $1 7. a3 Ba5 8. Nf3 Nf6 (8... cxd4 9. Qxd4 Qxd4 10. Nxd4 Bxc3+ 11. bxc3 { 1-0 (33) Marshall,F-Teichmann,R London 1902}) 9. Be3 Nc6 10. Qd3 (10. dxc5 Qxd1+ 11. Rxd1 Ne4 12. Rc1 Nxc3 13. bxc3 e5 14. Nd2 Bf5 15. f3 O-O-O 16. Ne4 Bc7 17. Be2 Bg6 18. g4 f6 19. Kf2 h5 20. h3 hxg4 21. hxg4 Rxh1 22. Rxh1 Bxe4 23. fxe4 g5 {1/2-1/2 (32) Lerner,K (2530)-Lukacs,P (2435) Polanica Zdroj 1986}) 10... cxd4 11. Nxd4 Ng4 {1-0 (58) Carlsen,M (2870)-Anand,V (2775) Chennai 2013 CBM 158 [Krasenkow/Mueller,Ka]}) 6... Qxd4 7. Bxb4 Qxe4+ {this is the starting position for the Slav gambit, otherwise known as the Marshall gambit, named after one of it's pioneers, Frank Marshall. Black has accepted a pawn sacrifice, but white has some serious compensation. To be specific; white has an unchallenged darksquare bishop, which is excelent in combination with the fact that black has weakened their darksquares. Also, white leads in development, a lead which could increase considering the enemy queen is exposed and vulnerable to tempo moves. And of course, black's king can't easily castle, altogether its a lot of compensation for a pawn, and in many cases even a second one. Black must fight for equality with every resourse available, often looking to rebuild the darksquare compelex with pawns, making use of some tactics when available while avoiding pitfalls, and even using the queen, at it's own risk, to create counter chances. This line has gathered lots of theory through out the years of it's play, and it's complicated nature makes it computer friendly, but it's evaluation isn't completely solved and it remains both playable albeit dangerous, for both sides} 8. Be2 $5 {This is the main continuation. White uses the bishop to get out of check and offers the g pawn, prefering to develop as quickly as possible in an attempt to exploit black's weaknesses before they can mobilize.} (8. Ne2 {is a tricky sideline which remains playable, but blocking one's development in a gambit position obviously isn't ideal and black has ways to leveling the game} Na6 (8... Nd7 $5 {is a another, simple, way for black to try for equality, aimed to meet Qd6 with ...Qe5} 9. Qd6 a5 $1 10. Ba3 Qe5 $1 {simplifications will give black even chances}) 9. Bf8 $5 {this is one of the ideas behind Ne2} Ne7 {black gives back material and begins counterplay} (9... Kxf8 $4 10. Qd8#) 10. Bxg7 { now black seems to have a couple reasonable continuations} Nb4 $5 {is sharp and reliable for black} (10... Rg8 11. Qd4 (11. Bc3 $5 e5 12. Qd6 {1-0 (43) Wells,P (2475)-Knaak,R (2530) Germany 1996}) 11... Qxd4 12. Bxd4 c5 13. Bc3 Nb4 14. Bxb4 cxb4 15. Nd4 $11 {1/2-1/2 (15) Atalik,S (2561)-Khenkin,I (2610) Bratto 2005 CBM 108 ext [Atalik,S]}) 11. Qd6 (11. Bxh8 {can lead to wild complications after} e5 $13 {[%cal Gb4d3,Gb4c2] /\ Nc2+ / d3+ with attack & quick development}) 11... Nd3+ (11... Nc2+ 12. Kd2 Nxa1 13. Bxh8 Qc2+ 14. Ke1 e5 15. f3 Be6 16. Bf6 Ng6 17. h4 Qf5 18. Bg5 h6 19. Bxh6 Rd8 20. Qc5 Qb1+ 21. Kf2 Nc2 22. h5 Nf4 $13 {0-1 (28) Vitiugov,N (2741)-Robson,R (2613) Antalya 2013 CBM 158 [Mikhalchishin,A]}) 12. Kd2 Nf5 13. Qxd3 Qxd3+ 14. Kxd3 Nxg7 { 1/2-1/2 (50) Wojtaszek,R (2733)-Giri,A (2750) Biel 2014 CBM 162 [Krasenkow,M]}) *

8th Move Alternatives

A game that I liked (ChessBase 13)
[Event "3...c6 Triangle System, Slav gambit"] [Site "?"] [Date "????.??.??"] [Round "?"] [White "Queen's Gambit Declined"] [Black "?"] [Result "*"] [ECO "D31"] [Annotator "kestenberg,tal"] [PlyCount "16"] 1. d4 d5 2. c4 e6 3. Nc3 c6 {The Triangle System} 4. e4 {Slav Gambit} dxe4 5. Nxe4 Bb4+ $5 6. Bd2 $5 Qxd4 7. Bxb4 Qxe4+ 8. Be2 $5 Na6 {This has proven to be the most reliable defense for black, immediatly addressing white's powerful darksquare bishop, and forcing it to decide where to go. in general black needs to use every possible oppertunity to defend actively, their position can't afford slow moves, so we will begin by looking at some of the alternatives here} (8... Nd7 {black prepares ...c5 to block the Bb4, but this doesn't get the king out of the center and affords white time to arrange their pieces well} 9. Nf3 c5 $5 (9... b6 $6 {is too slow and allows white a free hand, Nd2!?, Qd6!?, Qd2!? and the simple 0-0 all offer white good chances}) ( 9... Ngf6 10. Bd6 $5 {avoids ...c5}) (9... Ne7 10. Bxe7 $5 {is worth consideration, or just 0-0} Kxe7 11. Qd2 Re8 12. O-O-O $44 {1-0 (28) Vaisser,A (2580)-Namyslo,H (2225) Bern 1992 CBM 028 [Ernst]}) 10. Bc3 {now black has choice in how to develop, nevertheless white's coordinated pieces offer enough for the sacrificed pawn} Ne7 (10... f6 $6 11. Nd2 $1 (11. O-O Ne7 12. Nd2 { is also good}) 11... Qf4 (11... Qxg2 12. Bf3 $36) 12. Bh5+ $5 g6 13. Bf3 Ne5 ( 13... Ne7 14. Qe2 $36) 14. Be4 Nf7 (14... Nc6 15. Bxc6+ bxc6 $16) 15. O-O Qc7 16. Qf3 Qe7 (16... e5 17. Bd5 $16 {/\Ne4}) 17. Rfe1 $16 {1-0 (36) Dorfman,J (2595)-Ruzele,D (2495) Lyon 1994 CBM 045 [Dorfman]}) (10... Ngf6 {this knight development is less effective as the knights are redundant and white can prevent ...0-0 with} 11. Qd6 $1 {cutting off the black king is best here, black doesn't have a good way to challenge the queen} ({allowing castling is less promising but still OK} 11. Qd2 O-O) (11. O-O O-O) 11... Qg6 {here too, white has more than one good option} (11... Qc6 $6 {the attempt to challenge the queen only leads to white advantage} 12. Qxc6 ({the good alternative} 12. Qg3 $5 O-O 13. Rd1 $1 Nh5 14. Qh4 g6 $2 15. Rxd7 $1 Qxd7 16. g4 Qd8 17. gxh5 Qxh4 18. Nxh4 $18 {was played as early as 1-0 (28) Marshall,F-Schlechter,C Monte Carlo 1902}) 12... bxc6 {white's structure, and better pieces are more than enough} 13. Nd2 Bb7 14. O-O-O O-O-O 15. Bf3 $1 (15. Nb3 Ne4) 15... e5 $6 16. g4 $1 (16. Rhe1 Rhe8 17. Nb3 e4) 16... h6 17. h4 h5 (17... g5 18. hxg5 hxg5 19. Ne4 $16) 18. gxh5 $1 (18. g5 Ng4 19. Ne4 $44) 18... Kb8 (18... Nxh5 19. Ne4 $16) 19. Rhg1 Nxh5 20. Ne4 $1 (20. Bxh5 Rxh5 21. Rxg7 $16) 20... Bc8 21. Nd6 f6 22. Nf7 $18 {1-0 (28) Polgar,Z (2550)-Georgiev,K (2615) Pardubice 1994 CBM 042 [Polgar,Zsu]}) 12. Nd2 (12. Ne5 $5 Nxe5 13. Qxe5 $14 {[%cal Ge2f3] /\ Bf3 gives white simple play for an edge}) 12... a5 13. Bf3 Ra6 14. Qc7 O-O 15. O-O a4 16. Rfe1 Qd3 $6 17. Ne4 $1 Nxe4 18. Rad1 $1 Qxc4 19. Bxe4 Qxa2 20. Rd3 (20. Qg3 $1 $16) (20. Rxd7 $1 Bxd7 21. Qxd7 $16) 20... a3 21. Bxh7+ Kxh7 22. Rh3+ Kg8 23. Bxg7 e5 $1 24. Bxf8 Nxf8 25. Rg3+ Rg6 26. Rxg6+ fxg6 27. bxa3 Qd2 28. Rf1 Bf5 29. Qxc5 Qd4 30. Qc7 Be4 31. Rc1 Ne6 32. Qe7 Nf8 {1/2-1/2 (32) Stohl,I (2560)-Seitaj,I (2420) Moscow 1994}) 11. O-O (11. Qd2) (11. Bxg7 $6 Rg8 { [%csl Gg2]}) 11... O-O (11... f6 12. Bd3 Qf4 13. g3 (13. Re1 $5 $16) 13... Qc7 14. Nh4 {1/2-1/2 (49) Kan,I-Botvinnik,M Moscow 1954 EXT 2001 [RR]} (14. Ng5 $1) ) 12. Bd3) (8... Ne7 $6 {/\ ...Nd5!? to disturb the Bb4 and perhaps bring the knight to f4 with tempo} 9. Qd2 {avoiding the ...Nd5 ideas to take advantage of the loose Bb4 that ...Ne7 had in mind} (9. Nf3 Nd5 $5 {this is the idea behind Ne7, but even here white can fight for advantage with the precise...} 10. Nd2 $1 {this is better than Ba3?! ...Nf4} Qd4 11. Ba3 Nf4 12. O-O $44 { this gives white enough compensation, but the novelty 12.g3!? is pointed out by the computer}) 9... Ng6 $5 (9... Qxg2 $6 10. O-O-O $16) 10. Nh3 $5 {\/ ... Nf4 /\ Ng5} (10. Nf3 $6 Nf4) 10... f6 (10... c5 11. Bxc5 Qxg2 12. O-O-O Nd7 13. Ng5 $44 {0-1 (30) Rausch,S (2550)-Prang,E (2525) ICCF corr 1998}) 11. O-O-O { here i will include an illustrative game in which white's initiative was converted into a full point} Kf7 12. f3 Qh4 13. Bc5 $1 {to recycle the bishop on ...Na6 & supporting Nf2 /\ the advance of the kingside pawns} e5 14. Nf2 $1 f5 15. g3 Qf6 16. Rhf1 $1 {x-ray} Na6 17. Ba3 Be6 18. Ne4 $1 $18 {and white will regain material with a bonus} fxe4 19. fxe4 Nf4 20. gxf4 Rhd8 21. Bd6 Kg8 22. fxe5 Qh4 23. Qf4 Qxf4+ 24. Rxf4 {the rest is technique} Re8 25. Rdf1 Rad8 26. h4 Nb8 27. Kc2 Nd7 28. Kc3 Nf8 29. h5 h6 30. a4 Nh7 31. b4 a6 32. c5 Ng5 33. Bc4 Bxc4 34. Kxc4 g6 35. hxg6 Kg7 36. Rf7+ Kxg6 37. Rxb7 Nxe4 38. Rf4 Nd2+ 39. Kd3 Kg5 40. Rf2 {1-0 (40) Khalifman,A (2655)-Filippov,V (2510) Kazan 1995 CBM 051 [Khalifman]}) (8... Qxg2 $6 {is dangerous for black, but with many good options it is also possible for white to go wrong} 9. Bf3 $1 {completeing development is correct here} ({white isn't ready for} 9. Qd6 $6 Nd7 10. O-O-O Qxf2 {black can keep taking material} 11. Bf3 a5 $1 {with this in mind, white's bishop is driven to a3 where it is less flexible} ({white hopes for something like} 11... Qe3+ 12. Kb1 Qe5 13. Qd3 Ngf6 14. Nh3 c5 15. Bc3 $44 { with great compensation 1-0 (24) Parligras,M (2565)-Sveshnikov,E (2512) Albena 2013}) 12. Ba3 Qe3+ 13. Kb1 Qe5 $1 {black begins to consolidate} 14. Qd2 Ngf6 $15 {1-0 (24) Schiendorfer,E (2309)-Golf,E (2195) Germany 2010}) 9... Qg5 10. Ne2 {white is almost fully mobilized and black has yet to get anything but the queen off the back rank, many moves have been tried, but none fully neutralize white's initiative} c5 (10... Na6 11. Rg1 $1 {a useful inbetween move at this juncture} Qf6 12. Bc3 e5 13. Ng3 {/\ 0-0-0 was more than enough for white in 1-0 (51) Volkov,S (2636)-Grachev,B (2466) Krasnodar 2002}) (10... Ne7 11. Rg1 { is similar} Qh4 {here white has many poromising options, such as} (11... Qf6 $143 {here the queen falls victim to the knight maneuver Ne2-c3-e4-d6} 12. Nc3 $1 Nf5 13. Ne4 Qd8 14. Rxg7 $1 Qxd1+ 15. Rxd1 Nd7 16. Nd6+ Nxd6 17. Bxd6 Nf8 18. Be5 Nd7 19. Bc3 Ke7 $2 20. Bh5 $1 Rf8 21. Bd2 e5 22. Bg5+ Nf6 23. Rxh7 Bf5 24. Rh6 Bg6 25. Bxg6 {1-0 (25) Wood,B-Alexander,C London 1948}) 12. Rxg7 (12. Rg4 $5) ({and} 12. Bc3 {are also interesting}) 12... Qf6 13. Rg3 {grabbing a pawn back and maintaining pressure}) 11. Bc3 e5 {black tries to regain some control of the darksquares, but remains under developed} 12. Rg1 Qe7 13. Rxg7 Qf6 14. Rg3 Ne7 15. Be4 Nbc6 16. f4 {and white's play is going to be worth the pawn, which white regained with interest in...} Be6 $6 17. Qd6 Rd8 18. Qxc5 $16 {1/2-1/2 (40) Kan,I-Botvinnik,M Moscow 1952}) (8... c5 {isn't played often anymore, black's idea is lure the bishop to c5, where it could be vulnerable to tempo moves, before grabing the pawn on g2.} 9. Bxc5 Qxg2 (9... Nd7 { gaining the tempo this way could transpose after} 10. Bd6 Qxg2 11. Bf3 Qg5 { when the ...Nd7 may not be on it's ideal square}) 10. Bf3 {White has tried other moves in this position, but I will focus on this simple, and most played move} Qg5 {retreating the queen with tempo, this is part of the idea behind ... c5 giving back a pawn} 11. Bd6 (11. Ba3) (11. Qd6 $5 {is the computer's first choice, but rare in practice}) 11... Ne7 (11... Nd7 {is slow to develop} 12. h4 $5 (12. Ne2 $142 $1) 12... Qa5+ $5 13. b4 Qf5 14. Qb3 Ngf6 15. O-O-O $13 { 1-0 (23) Piket,J (2575)-Van der Werf,M (2415) Breda 1998 CBM 065 [Piket,L]}) ( 11... Nc6 {gives white the aditional option to play} 12. Bxc6+ $5 (12. Ne2 Nge7 13. Rg1 {would transpose into 11...Ne7}) 12... bxc6 13. Qf3 (13. Nf3 Qa5+ 14. b4 Qf5 15. Qe2 Nf6 16. Rg1 {1-0 (34) Vaisser,A (2380)-Cheremisin,F Odessa 1977} ) 13... Bd7 14. Ne2 Ne7 15. Rg1 Qf6 16. Qa3 {1-0 (22) Wade,R-Fichtl,J Marianske Lazne 1956}) 12. Ne2 Nbc6 ({there aren't any better alternatives} 12... Qf6 $6 13. Nc3 Nf5 $6 14. Nb5 $1 Na6 15. Qb3 Nxd6 16. Nxd6+ Kf8 17. Qa3 $16 {1-0 (33) San Segundo Carrillo,P (2480)-Korneev,O (2540) Linares 1995}) ( 12... O-O 13. Rg1 $16) 13. Rg1 {this is a main line for the 8...c5 variation, the example game shows some dangers for black} Qf6 (13... Qa5+ 14. Nc3 {Kf1!?} Nf5 15. Be4 Bd7 16. Bxf5 $1 exf5 17. Qe2+ Be6 18. O-O-O {1/2-1/2 (44) Hjartarson,J (2570)-Van der Werf,M (2400) Reykjavik 1996 CBM 052 [Hjartarson]}) 14. Nc3 (14. Qb3 Nf5 15. Bxc6+ bxc6 16. Ba3 {1/2-1/2 (27) Von Baudissin, G-Juehe,H Guetersloh 1952}) 14... Nd4 $5 15. Bh1 (15. Be4) 15... Nef5 (15... e5 $5 $13) 16. Ne4 Qd8 17. Rxg7 e5 18. Qh5 Be6 19. O-O-O $44 Qa5 $2 20. Qg5 $1 Kd7 21. Nc5+ Qxc5 22. Bxc5 Rac8 23. Rxf7+ Bxf7 24. Qxf5+ {1-0 (24) Lachmann, H-Juehe,H Minden 1951}) *

9th Move Alternatives

A game that I liked (ChessBase 13)
[Event "3...c6 Triangle System, Slav gambit"] [Site "?"] [Date "????.??.??"] [Round "?"] [White "Queen's Gambit Declined"] [Black "?"] [Result "*"] [ECO "D31"] [Annotator "kestenberg,tal"] [PlyCount "18"] 1. d4 d5 2. c4 e6 3. Nc3 c6 4. e4 dxe4 5. Nxe4 Bb4+ $5 6. Bd2 $5 Qxd4 7. Bxb4 Qxe4+ 8. Be2 $5 Na6 {This has proven to be the most reliable defense for black, immediatly addressing white's powerful darksquare bishop, and forcing it to decide where to go. in general black needs to use every possible oppertunity to defend actively, their position can't afford slow moves} 9. Bd6 $5 (9. Bc3 { has been played for 100 years, black has found some defensive ideas, one typical game for the evaluation went...} f6 $1 10. Qd6 $6 (10. Nf3 $142 Ne7 11. O-O O-O 12. Re1 $132) 10... Ne7 11. O-O-O e5 $1 12. Bh5+ (12. Qd8+ $6 Kf7 13. Qxh8 Bf5 14. Bd3 Qxd3 15. Rxd3 Rxh8 16. Rd2 Nc5 $44) 12... Ng6 $11 ({black could have played to win with} 12... g6 $5 $15) 13. Qd8+ {white has a draw} Kf7 14. Rd7+ Ke6 15. Rd6+ Kf7 16. Rd7+ Ke6 17. Rd6+ Kf7 {1/2-1/2 (17) Gurevich,M (2688)-Vallejo Pons,F (2559) Dos Hermanas 2001 CBM 124 [Kuzmin,Alexey]}) (9. Ba5 {is a more modern try, here too black has discovered defensive resources} b6 (9... f6 $144 $5 {is also good for even chances} 10. Qd8+ Kf7) (9... Bd7 10. Nf3 Nf6 11. Qd6) 10. Qd6 Bd7 $1 (10... Bb7 $2 11. O-O-O c5 12. Qd7+ Kf8 13. Qd6+ Ke8 14. Bc3 $16 {1-0 Kobalia,M (2643)-Sveshnikov,E (2557)/Stepanakert 2004/CBM 100 (23)}) 11. Bc3 f6 12. Nf3 (12. O-O-O $5 O-O-O 13. Qa3 Kb7 14. Bf3 Qf4+ 15. Rd2 Qc7 $1 16. Ne2 e5 $11 {1/2-1/2 Atalik,S (2581)-Pavasovic,D (2573)/ Nova Gorica 2003/}) 12... Rd8 (12... Ne7 $144 13. O-O-O Qxe2 14. Qxd7+ Kf7 15. Qd4 Rhd8 16. Qg4 Kf8 $13 {1/2-1/2 Volkov,S (2623)-Frolyanov,D (2544)/Moscow RUS 2008/The Week in Chess 693 (48)}) 13. Qg3 $6 (13. Qa3 $5 Nc5 14. Qxa7 $2 { Rd1!} Nd3+ 15. Kf1 Nf4 16. Re1 e5 $17) 13... Qg6 14. Nh4 $6 (14. Qd6) 14... Qxg3 15. hxg3 Nh6 $15 16. f4 $6 Nc5 17. O-O-O Ne4 18. Be1 c5 $17 {white is fighting for a draw} 19. g4 O-O 20. Bf3 Bc6 21. Rxd8 Rxd8 22. g5 Nf5 23. Nxf5 exf5 24. gxf6 gxf6 25. Rh5 Kg7 26. b3 Kg6 27. Rh3 h6 28. Kc2 Bb7 29. Bh5+ Kg7 30. Rd3 Rxd3 31. Kxd3 Nd6 32. g3 Be4+ {1/2-1/2 (32) Vallejo Pons,F (2660) -Pavasovic,D (2597) Crete 2007 CBM 124 [Kuzmin,Alexey]}) 9... Qxg2 $5 {this has become the main defense. Black grabs a second pawn, hoping that the inclusion of ...Na6 and Bd6 (which closed the d line) will allow them to survive, but I will not include this here, rather the other options at black's disposal.} (9... e5 {while black would like to develop the Bc8 and fight for the darksquares. it is a bit dangerous for black to play in the center this way while so underdeveloped. black must be very cafeful to get a reasonable game} 10. Nf3 {white should get on with simple development} Bg4 (10... f6 { leads to play similar to lines where black starts with ...f6, black is too slow, e.g.} 11. O-O Bf5 12. Nxe5 $1) 11. O-O $5 (11. Nxe5 {only offers equality in the endgame} Qxe2+ 12. Qxe2 Bxe2 13. Kxe2 Nh6 $11) 11... O-O-O 12. b4 {this is more ambitious, going after black's king.} (12. Bd3 {this also leads to an endgame with even chances if black plays precisely} Qf4 13. Bxe5 Qxe5 14. Nxe5 Bxd1 15. Bf5+ Kc7 16. Nxf7 Nh6 $1 $11 {with this black is ok} ({ bad for black are} 16... Ne7 $6 17. Bxh7 $1 {1-0 (47) Tal,M (2625)-Dorfman,J (2550) Tbilisi 1978}) ({and} 16... Bh5 $6 17. Nxd8 $1 Kxd8 18. g4 Nh6 19. Rad1+ Kc7 20. Rd7+ Kb6 21. Rxg7 Nxf5 22. gxf5 Rf8 23. Re1 Nc5 24. b4 Nd3 25. Ree7 { 1-0 (36) Aronian,L (2752)-Vallejo Pons,F (2650) Morelia/Linares 2006 CBM 112 [Dautov]})) 12... Nf6 (12... Nxb4 $6 {puts the knight in a precarious position, when black may fall victim to some tactics} 13. Re1 $1 {is strong} Nf6 14. Nd2 $1 {breaking the pin on the d line} Bxe2 15. Rxe2 $1 Qxe2 {otherwise the Nb4 is lost} 16. Qxe2 Rxd6) 13. c5 $1 (13. Re1 Bxf3 14. Bxf3 Qxc4 15. Rxe5 { 1-0 (28) Mamedyarov,S (2709)-Tregubov,P (2556) Reykjavik 2006} Nc7 $5 $13) 13... Ne8 $5 (13... Nxb4 14. Rc1 {including h3!? first maybe an improvement} Nbd5 15. Rc4 {offers white good compensation 1-0 (38) Gumula,D (2387) -Sveshnikov,E (2504) Pardubice 2007}) (13... Qxb4 $2 14. Bxa6 $18) 14. Bd3 $1 { white saves the dark square bishop} Qf4 $5 (14... Qd5 {runs into the rather spectacular pin breaking} 15. Nxe5 $3 Bxd1 16. Bf5+ {the point} Qe6 17. Bxe6+ fxe6 18. Raxd1 $14) (14... Qxb4 $2 15. Rb1 $18 {is trouble for black}) 15. Bxe5 Qxb4 16. Rb1 {black is walking a very thin line} Qa5 (16... Qxc5 $2 17. Bxa6 $3 {is winning for white}) 17. Qc2 Nxc5 18. Rb5 {after this tactical try black was able to hold with some accurate play in...} (18. Bf5+ $5 Bxf5 19. Qxf5+ { gives white good compensation and better chances to play on, for example} Nd7 20. Qxf7 Rf8 21. Qb3 $44) 18... cxb5 19. Qxc5+ Nc7 20. Rc1 Rxd3 $1 21. Bxc7 Rd1+ $1 22. Rxd1 Qxc7 23. Qxa7 Bxf3 24. gxf3 Qc2 25. Qd4 $11 {1/2-1/2 (31) Vitiugov,N (2550)-Frolyanov,D (2497) Sochi 2006}) (9... b6 {is the old main line, black intends to fianchetto with ...Bb7, but this is, as is the case with most alternatives to the main line, slow, and white can stir up an initiative} 10. Nf3 Bb7 11. O-O {this logical continuation looks best, white gets the king to safety, which black has trouble with, before proceeding with further action. Black doesn't have a good equalizer here} (11. Ne5 {this agressive move has been known for a long time as well} f6 12. O-O $1 {this is white's idea, a good one to know for similar positions, but here black can defend by eventually giving back the material} fxe5 13. Bh5+ g6 14. Re1 Qh4 ( 14... Qxc4 $5 {this looks simpler, giving back material after...} 15. Be2 Qd5 16. Qxd5 cxd5 17. Bxa6 Bxa6 18. Bxe5 Nf6 19. Bxf6 O-O $11 {1/2-1/2 (26) Doric, D (2382)-Geller,J (2469) Pardubice 2005}) 15. Bg4 Rd8 16. Rxe5 Nc5 17. b4 Nh6 18. bxc5 Qxg4 19. Qxg4 (19. f3 $5 {/\ Rxe6+ looks like an improvement for white here}) 19... Nxg4 20. Rxe6+ Kd7 21. Re7+ Kc8 22. Rae1 bxc5 23. Rc7+ Kb8 24. Rb1 Rxd6 25. Rbxb7+ Ka8 26. Rxa7+ Kb8 27. Rab7+ {1/2-1/2 (27) Okrajek,A (2205)-Beltz,R Rostock 1979 EXT 2002 [Neukirch,D]}) 11... Rd8 {as other natural moves fail to impress, but this is no better} (11... c5 {is premature} 12. Nh4 $5 {this unexpected move turns out to be very strong, white prepares to challenge the long diagonal} (12. Qa4+ {is also good, and gives white an endgame edge after} Qc6 13. Qxc6+ Bxc6 14. Ne5 Rd8 {½-½ (34) Milos,G (2589) -Goh,W (2413) Turin 2006 and now the tricky move, which was played a move later in the referenced game...} 15. Bf8 $5 $14 Kxf8 $140 16. Nxc6 Rd6 17. Nxa7 ) 12... O-O-O $5 (12... Qxh4 $2 13. Qa4+ $1 Kd8 14. Rad1 $18) 13. Bf3 Qxc4 ( 13... Qxh4 $2 14. Bxb7+ Kxb7 15. Qf3+ $18) 14. Bxb7+ Kxb7 15. Qf3+ Qd5 16. Qxf7+ Ka8 17. Rad1 $14) (11... O-O-O 12. Ne5 $1 {is uncomfortable for black} Qf5 {black's queen is misplaced} (12... Qf4 13. Ng6 $14 {or better yet, Bh5!}) (12... Nh6 $2 13. Bf3 $1) 13. g4 $1 Qf4 (13... Qf6 14. f4 h6 15. Bf3 Ne7 16. Qd2 $16) 14. Ng6 Qxd6 15. Qxd6 Rxd6 16. Nxh8 Rd2 17. Rfe1 f6 18. Rad1 Rxb2 19. Nf7 Kc7 20. Nd6 Nc5 21. Ne8+ Kc8 22. Nxg7 {1-0 (47) Sage,F (2395)-Lorin,F (2040) ICCF email 2006}) 12. Ng5 $1 {now this knight hop causes black problems} (12. Qd2 $5 {/\ Rd1 to support the Bd6 is also good}) 12... Qf5 (12... Qg6 13. f4 {/\ Bh5} Nf6 14. Re1 Rd7 15. Bd3 Qh5 16. Bf5 $5 Qxd1 17. Raxd1 $16) 13. f4 $1 {white supports the knight with the idea to play g4 to harass the queen, and / or Bh5 first} Ne7 (13... h6 14. Bg4 $1) (13... Nf6 14. g4 $1) (13... Nh6 14. Bh5 $1 {/\ Nxe6!}) 14. Bh5 $1 O-O 15. g4 $1 Qf6 16. Qc2 $1 Ng6 (16... g6 17. Be5 $1) 17. Bxf8 Rxf8 18. Bxg6 hxg6 $18 {1-0 (28) Kosyrev,V (2546)-Yudin,S (2442) Sochi 2006}) ({black's remaining alternatives are not as testing} 9... f6 $6 {/\ ...e5 to rebuild the darksquares and free the Bc8 isn't in time for black, for example, after the natural moves} 10. Nf3 e5 11. O-O Bf5 {white can start the sacrificial attack with} (11... Be6 12. Bd3 Qg4 13. Re1 {is also promising for white, who can start an attack should black ...0-0-0 with c5 & Re4!?}) 12. Nxe5 $1 $18 fxe5 $140 13. Bh5+ {/\ Re1}) (9... Ne7 $6 {is dubious. the idea to play ...Nf5-xd6 is too slow and dangerous for black's king. the ... Ne7 is more of a target for white than an aid to the defense's king.} 10. Nf3 Nf5 {can be met with the pseudo piece sacrifice} (10... f6 11. O-O c5 12. Qd2 { Re1!} Bd7 13. Rad1 Rd8 $2 14. Ng5 $1 Qf5 15. Bxe7 Kxe7 16. Qd6+ Ke8 17. Rd5 e5 18. f4 Nb4 19. Bh5+ g6 20. g4 Nxd5 21. gxf5 Bxf5 22. Qxc5 Nxf4 23. Rxf4 exf4 24. Qxf5 {1-0 (24) Jobava,B (2556)-Izoria,Z (2547) Tbilisi 2002}) 11. O-O $1 Nxd6 12. Qxd6 {one game ended abruptly after} Bd7 $4 (12... Qxe2 $4 13. Rad1 $18) (12... f6 13. Rad1 Kf7 14. Bd3 Qg4 15. c5 e5 16. Bxa6 {Nxe5!} bxa6 17. Qc7+ Kg6 18. Qxc6 Be6 19. h3 Qc4 20. b3 Rac8 21. Qd6 Qxc5 22. Qxe6 Rhe8 23. Qg4+ Kf7 24. Rd7+ {1-0 (24) Dale,A (2228)-Guramishvili,S (2398) Wijk aan Zee 2014}) 13. Bd3 $1 {1-0 (13) Camus,B (2065)-Piermee,E (2161) Champagne Ardenne 2003}) (9... Bd7 $6 {doesn't help black much, castling 0-0-0 isn't very safe for the king and the ...Bd7 isn't useful} 10. Nf3 c5 11. Ne5 $5 ({white could simply} 11. O-O $5) 11... f6 $1 {this is blacks only reasonable defense, and a tricky one!} (11... Bc6 $6 12. Nxc6 bxc6 13. O-O $16 {1-0 (22) Taimanov, M-Steiner,H Saltsjobaden 1952}) 12. O-O $5 ({black's idea can be seen after} 12. Nxd7 {when} O-O-O $1 {gives them a fine game}) 12... fxe5 {was ½-½ (44) Ionescu,M (2389)-Chirila,I (2339) Bucharest 2006 when white should have continued} 13. Bh5+ $1 Kd8 (13... g6 14. Bf3 Qf5 15. Bxb7 Rd8 16. f4 $1 e4 17. g4 Qf7 18. Be5) 14. Qb3 (14. Bf3 $5 Qd4 15. Bxb7) 14... Nb4 15. Rad1 Qf5 16. Bxc5 $1 Qxh5 17. Qxb4 b6 ({or} 17... Rc8 18. Qxb7 Nf6 19. Qxa7) 18. Bxb6+ $1 axb6 19. Qxb6+ Ke8 20. Rxd7 $1 Kxd7 21. Qb7+ Ke8 22. Qxa8+ Ke7 $1 23. Qb7+ Kf6 24. Qc8 {[Ruslan Scherbakov]}) *

The Main Line

A game that I liked (ChessBase 13)
[Event "3...c6 Triangle System, Slav gambit"] [Site "?"] [Date "????.??.??"] [Round "?"] [White "Queen's Gambit Declined"] [Black "?"] [Result "*"] [ECO "D31"] [Annotator "kestenberg,tal"] [PlyCount "43"] 1. d4 d5 2. c4 e6 3. Nc3 c6 4. e4 dxe4 5. Nxe4 Bb4+ $5 6. Bd2 $5 Qxd4 7. Bxb4 Qxe4+ 8. Be2 $5 Na6 9. Bd6 $5 Qxg2 $5 {this has become the main defense. Black grabs a second pawn, hoping that the inclusion of ...Na6 and Bd6 (which closed the d line) will allow them to survive.} 10. Qd2 $1 {this is the critical test for black, white offers a rook, but it can no be taken} (10. Bf3 $6 Qg5 { is a better version for black of the line where black plays ...Qxg2 without ... Na6 and Bd6} 11. Ne2 Ne7 12. Rg1 Qa5+ 13. Nc3 Nf5 $15 {0-1 (21) Shyam,N (2398) -Adhiban,B (2542) Chennai 2011}) (10. Qd4 $6 Nh6 $1 {hunting down the Bd6 was good for black in} 11. O-O-O Nf5 $17 {1-0 (34) Jobava,B (2566)-Potkin,V (2493) Batumi 2002}) 10... Nf6 $1 {black needs to gain time, in this case /\ ...Ne4} ( 10... Qxh1 $2 11. O-O-O $1 {puts black's queen in danger as retreating} Qe4 { is met by the spectacular clearance sacrifice} 12. Be7 $3) (10... Ne7 $6 11. O-O-O $1 {is also good for white}) 11. Bf3 $1 ({avoiding} 11. O-O-O Ne4 $15) 11... Qg6 12. O-O-O (12. Ne2 e5 13. O-O-O {transposes}) 12... e5 $1 {black must prepare the development of the Bc8 and 0-0-0, the ability to give back a pawn is an important defensive idea for black} (12... Ne4 $2 {is no longer good } 13. Bxe4 Qxe4 14. Qg5 $1 $18) 13. Ne2 (13. Bxe5 {this is white's alternative, and a line that could arise via another move order} Be6 {this looks to improve on castling right away, again, black should develop as actively as possible} ( 13... O-O $6 {is too risky as white develops a very strong position} 14. Ne2 { /\ Rg1} Qf5 15. Qe3 $1 Nb4 16. Nd4 $1 Nxa2+ 17. Kd2 Rd8 18. Ke2 $16 Qxe5 19. Qxe5 Re8 20. Qxe8+ Nxe8 21. Nxc6 bxc6 22. Rd8 {1-0 (22) Braun,A (2536)-Van der Werf,M (2389) Wijk aan Zee 2008}) 14. Ne2 {white continues mobilizing, /\ Rg1} Qf5 $1 15. Bf4 $1 {this seems to be the critical position for the Bxe5 line, black has tried taking the c pawn with ...Bxc4 or bringing the queen over to caputre it with ...Qc5, in both cases it looks like white has at least enough for their material} (15. Qe3 $6 Nb4 $1 {is unpleasant here} 16. Nd4 Nxa2+ 17. Kd2 O-O-O $1 {this is the improvement on 13...0-0}) 15... Bxc4 (15... Qc5 16. Nc3 Qxc4 17. Be2 Qc5 18. Bxa6 bxa6 19. Bd6 {with a good opposite color bishop middlegame for white in 1-0 (56) Gupta,A (2565)-Gaponenko,I (2428) Paleochora 2009}) 16. Rhg1 (16. Ng3 Qc5 17. Be3 Qb4 18. Nf5 Qxd2+ 19. Rxd2 {as in 1-0 (97) Gupta,A (2551)-Ashwin,J (2436) Gaziantep 2008 is given as equal by the computer }) 16... Bxa2 17. Qe3+ Qe6 18. Be5 Qe7 19. Qg5 Nd7 20. Qxe7+ Kxe7 21. Bd6+ Kf6 22. Nc3 (22. Bg3 $5 $44) 22... Bb3 23. Ne4+ Ke6 24. Ng5+ Kf6 25. Ne4+ Ke6 26. Ng5+ Kf6 27. Ne4+ Ke6 28. Ng5+ Kf6 29. Ne4+ Ke6 {1/2-1/2 (29) Doric,D (2456) -Pavasovic,D (2568) Slovenia 2011}) 13... Bg4 $5 {a logical move, and the most challenging, black develops the Bc8 with tempo and looks to exchange off white's bishop pair} (13... Be6 14. Bxe5 {leads back to the 13.Bxe5 lines} (14. Rhg1 Qf5 15. Qe3 {is an alternative for white, black seems ok in practice})) 14. Bxg4 $1 {best} (14. Rhg1 $6 {is also possible, but white walks a tightrope on the difficult end of complications, and can easily lose the balance, as in.. .} O-O-O 15. Qe3 h5 16. h3 Rxd6 $1 17. Rxd6 Nb4 18. Qb3 $1 Qh6+ 19. Kd1 Bxf3 20. Qxf3 Qh7 21. Nc3 Qc2+ 22. Ke1 e4 23. Qf5+ Kb8 24. Rxg7 Nd3+ 25. Kf1 Qc1+ 26. Kg2 Nf4+ 27. Kg3 ({or} 27. Kh2 $6 Ng4+ 28. Rxg4 $2 hxg4 29. Rd1 Rxh3+ 30. Kg1 Ne2+ 31. Kf1 Ng3+ 32. fxg3 Rh1+ 33. Kg2 Rxd1 34. Nxd1 Qxd1 $19 {0-1 (58) Moiseenko,A (2630)-Pavasovic,D (2567) Dresden 2007 CBM 118 [Stohl,I]}) 27... Qg1+ 28. Kxf4 Qxf2+ 29. Kg5 $4 (29. Ke5 Qc5+ 30. Kf4 Qxd6+ 31. Qe5 Qxe5+ 32. Kxe5 {sees white fighting to draw}) 29... Qg3+ 30. Kxf6 Qxd6+ 31. Kg5 Qh6+ { 0-1 (31) Van Wely,L (2674)-Pavasovic,D (2567) Dresden 2007}) 14... Nxg4 { now white has a choice in how to continue} (14... Qxg4 $6 15. Bxe5 $16 { is better for white}) 15. f3 {a sacrificial continuation, white gets a dangerous initiative, but objectively black can hold} (15. Ba3 $5 {this novelty is worth considering to get original positions} Qe6 (15... Qh6 16. f4 $1) 16. Nf4 $1 exf4 (16... Qxc4+ 17. Kb1 {is easier for white} Qe4+ 18. Ka1 Qd4 19. Qxd4 exd4 20. Rxd4 (20. Rhe1+)) 17. Rhe1 Ne3 18. fxe3 f3 $1 {keeping lines closed} 19. Rg1 g6 20. Qd4 Rg8 21. b3 c5 $5 22. Qf4 {keeping the kingside pawns in check, white will have enough compensation for a pawn after taking one of black's} f5 23. Qxf3 {with even chances}) 15... Nf2 (15... O-O-O 16. fxg4 {isn't really enough for black dispite a draw in ½-½ (30) Khruschiov,A (2514)-Lastin,A (2622) Voronezh 2008} Qxg4 (16... Rhe8 17. Nc3 Re6 18. c5 Nxc5 19. Qe3 $16) 17. Qc2 $16 ({or} 17. c5 Nxc5 18. Qe3 $16)) 16. Bxe5 Nxd1 17. Rxd1 {white for sure has enough for their sacrificed material, but black, though not in practice, has found some defences} Nc5 $1 (17... Qe6 $2 18. Bxg7 Rg8 19. Nf4 Qe7 20. Nh5 $18) 18. Nf4 (18. Qd4 $5 b6 $2 (18... Qg5+ $5 {Was played in a Corr. game, and looks like a convincing way to hold for black.} 19. Nf4 (19. Bf4 Qe7 20. Qxg7 Rf8 21. Bh6 Ne6 22. Qxh7 Ng5 23. Qg7 Ne6) 19... Ne6 $1 20. Qd7+ Kf8 21. Bb8 $1 Rxb8 22. Qd6+ Ke8 23. Qd7+ Kf8 24. Qd6+ Ke8 $11 {½-½ (25) Loeffler,W (2340)-Schulz,K (2379) ICCF email 2008}) 19. b4 Ne6 20. Qd7+ Kf8 21. Qxc6 Re8 22. Bd6+ {1-0 (22) Iljin,T (2388)-Potkin,V (2610) St Petersburg 2014}) 18... Qg5 19. Qd6 {in the one master game to reach this position in the database white got an endgame advantage} Qe7 $6 (19... Ne6 $5 {looks best, and leads back to the note on 18.Qd4} 20. Qd7+ Kf8 21. Bb8 $1 Rxb8 22. Qd6+ Ke8 23. Qd7+ Kf8 24. Qd6+ Ke8 25. Qd7+ Kf8 {white reasonably chose to draw rather than play the risky alternatives ½-½ (25) Loeffler,W (2340)-Schulz,K (2379) ICCF email 2008}) 20. Qxe7+ Kxe7 21. Bd6+ Kf6 22. Bxc5 {eventually black held a draw but white's two pieces look preferable ½-½ (36) Gajewski,G (2504) -Kempinski,R (2567) Ustron 2006} *