Annotated Game #118: A slip in the Slav; or, the case of the missing pawn capture

Two main features of this third-round tournament game stand out for me.  First is the seeming slip of 6...b4? which is a creatively bad pawn sacrifice in the opening.  Even though my opponent did not directly punish it, the decision led to problems in the initial phase of the game.  Second is the mutual blindness of myself and my opponent, lasting for a large chunk of the game, over the possibility of Black's pawn capture (bxa3) on the queenside.  At a number of points it would have given me a significant, perhaps decisive, advantage.  It is an interesting example of the importance of not dismissing CCT options, especially obvious ones.  I can say that this was primarily a thinking process failure on my part, since I failed to re-examine the possibilities in the position as the game went on, after dismissing the idea to begin with.

[Event "?"] [Site "?"] [Date "????.??.??"] [Round "?"] [White "Class C"] [Black "ChessAdmin"] [Result "1-0"] [ECO "D15"] [Annotator "ChessAdmin/Houdini"] [PlyCount "91"] [EventDate "2012.01.??"] [EventType "swiss"] [EventRounds "7"] {D15: Slav Defence: 4 Nc3 a6 and gambit lines after 4 Nc3 dxc4} 1. d4 d5 2. c4 c6 3. Nf3 Nf6 4. Nc3 dxc4 5. e3 b5 6. a3 {a quite passive move.} (6. Ne5 { is an aggressive try, for example:} Bb7 7. a4 a6 8. b3 cxb3 9. Qxb3 e6 10. axb5 axb5 11. Rxa8 Bxa8 12. Nxb5 cxb5 13. Bxb5+ Nfd7 14. O-O Bd5 15. Qa4 f6 16. Nxd7 Nxd7 17. Bd2 Bd6 18. Rc1 Ke7 19. Qa7 Bxh2+ 20. Kxh2 Qb8+ {Ricardi,P (2470) -Ginzburg,M (2400) Buenos Aires 1994 1-0}) (6. a4 {is standard here, though.} b4 {and Black plays ...a5 after the Nc3 retreats.}) 6... b4 $146 {Black scores extremely well from this position with just about any other reasonable move. Here my newfound creativity, based on examining the standard idea of ...b4 regardless of White played, was unsound.} (6... Bb7 7. g3 e6 8. Bg2 a6 9. O-O Be7 10. b3 cxb3 11. Qxb3 Nbd7 12. a4 O-O 13. axb5 cxb5 14. Ba3 Rc8 15. Bxe7 Qxe7 16. Ne2 Nb6 17. Kh1 Nc4 18. Rfc1 Bxf3 19. Bxf3 Nd2 20. Qd3 Nxf3 21. e4 { Le,T-Nguyen Thi Hanh (1969) Da Lat VIE 2011 0-1 (39)}) (6... Bf5 7. Nh4 Bg6 8. Be2 e6 9. Nxg6 hxg6 10. Bf3 Nd5 11. e4 Nxc3 12. bxc3 Nd7 13. Bf4 Qa5 14. Qc1 Be7 15. h3 Rc8 16. Bd1 g5 17. Bd2 c5 18. Qb2 cxd4 19. cxd4 c3 20. Qa2 cxd2+ 21. Kf1 {Kovalenko,S (2300)-Zubashev,V Kharkov 2004 0-1}) (6... g6 7. e4 $11) 7. Na2 {White decides not to take the pawn on offer, trusting too much that Black knew what he was doing.} (7. axb4 e6 8. Bxc4 Bxb4 $16 {and although material is equal, White now has a lead in development, superior piece activity, and only one weak isolated pawn versus two for Black.}) 7... a5 8. Bxc4 e6 9. O-O Nbd7 {Black is behind in development, says Houdini via the Fritz interface.} 10. b3 {this allows Black to immediately equalize.} (10. Bd2 {would have both developed a piece and forced a resolution of the queenside pawn structure.} bxa3 11. bxa3 Bxa3) 10... Be7 11. Qc2 Bb7 {defending the c-pawn and moving to a future potentially useful diagonal.} 12. Bb2 {better to do this after the pawns are exchanged.} (12. axb4 axb4 13. Bb2 O-O $11) 12... O-O {here I didn't even consider the pawn capture as a candidate move, thinking it was more important to move along with development.} (12... bxa3 {is simple and annoying for White.} 13. Bc1 $15 {Black's weak a3 pawn will eventually fall, but in the meantime it's at least helped retard White's development and restricted his dark-square bishop.}) 13. Nc1 {White needs to get the knight back in the game.} c5 {this pawn break is eventually needed in all variations.} 14. Qe2 Rc8 { played on the general principle of activating your rooks in the middlegame. However, this rook could be useful on the a-file and did not need to move.} ( 14... cxd4 15. Nxd4 Nb6 16. axb4 (16. Bd3 bxa3 17. Bxa3 Bxa3 18. Rxa3 e5 $15) 16... Nxc4 17. bxc4 axb4 {for example would give Black the two bishops and somewhat better prospects for his pieces.}) 15. Nd3 cxd4 16. Bxd4 $6 (16. axb4 dxe3 17. bxa5 exf2+ 18. Nxf2 Bd5 $11) (16. Nxd4 {also works fine for White.}) 16... Nb6 $6 (16... bxa3 $17 {continues to be resolutely ignored by Black, who could obtain a significant advantage.}) 17. Nde5 (17. axb4 Nxc4 18. bxc4 axb4 $11) 17... Nxc4 18. Nxc4 Ba6 {the double pin (against queen and rook) here is annoying but not decisive.} (18... a4 {with a pawn sacrifice is a better version of the idea, the point being if} 19. bxa4 $2 {then} (19. axb4 axb3 20. Na5 $11) 19... Ba6 {comes with much more bite against the underprotected knight.} 20. Rfc1 bxa3 21. Nfe5 Qd5 $19) 19. Rac1 $2 {White is obviously concerned about protecting the Nc4 sufficiently, but this is a mistake.} (19. Rfd1 {is an improved rook development, lining up against Black's queen and moving away one of the pieces behind the pinned knight.}) 19... Qd5 $6 { here I wanted to get the queen into the action and had more desire to attack than calculate.} (19... a4 {now interestingly is much stronger for Black, due to the White rook having moved off the key a-file.} 20. axb4 axb3 21. Rfd1 Bxb4 22. Nfe5 Qd5 23. Ba1 Bxc4 24. Nxc4 Qb5 $19) (19... bxa3 {is simple and very good for Black.}) 20. Nfe5 {both White and Black continue to ignore the queenside pawn threats.} (20. Rfd1) 20... Qe4 21. Qb2 {moving one piece out of the pin, but this still allows Black to grab the a3 pawn if he wants.} (21. axb4 Bxb4 22. Rfd1 $11) 21... Rfd8 (21... bxa3 22. Qa1 Qh4 $17) 22. Rfe1 (22. axb4 Bxb4 23. Bb6 Re8 {and White has a space advantage plus threats to the a5 pawn, although Black is not without resources. For example:} 24. Ra1 Qf5 25. Rfc1 Ng4 26. Nxg4 Qxg4 27. Bxa5 Bxc4 28. bxc4 Bxa5 29. Rxa5 Rxc4 $11) 22... Nd7 {in my first quick review of the game, I blamed this move for the loss. In fact, it's just fine, although at first glance it denudes Black's kingside of defenders and loses the g7 pawn.} 23. Nxd7 Rxd7 24. Bxg7 $2 Bxc4 {this is the good idea for continuing the attack, although psychologically at this point I felt I was under heavy pressure to justify the loss of the g-pawn and did not play optimally.} (24... bxa3 $1) 25. Rxc4 (25. bxc4 $5 bxa3 26. Qa1 Rxc4 $17) 25... Rxc4 26. bxc4 Qg4 $2 {blindness to the queenside pawn capture continues. This is the final turning point in the game, as psychologically I become negative about my remaining chances.} (26... bxa3 27. Qa1 Rd2 $19) 27. Bd4 $14 {I had spotted this defense earlier but could not see anything better for Black.} h5 {an attempt at an attack, played out of feelings of desperation.} ( 27... e5 {I had seen this as a possibility but could not see the most effective continuation, so rejected it.} 28. h3 (28. Bxe5 Rd1 $11) 28... Qe6 29. Bxe5 bxa3 30. Qb5 $14 {and Black has decent if not full compensation for the pawn, as his passed a-pawn is more advanced, with another one behind it.}) 28. h3 $16 Qh4 29. Rc1 {White plans c5, notes Houdini.} (29. axb4 {is an improved version of the idea.} Bxb4 30. Rc1 $16) 29... f6 $2 {this loses more quickly, but I had been concerned about the threat of Bh8 followed by Qg7.} ( 29... e5 30. Bxe5 bxa3 $16 {puts up a bit more resistance}) (29... bxa3 { is no good because of} 30. Qb8+ Rd8 (30... Bf8 31. c5 $18) 31. Qe5 $18) 30. c5 $18 Kf7 31. c6 Rd8 32. c7 Rc8 33. Qe2 Bd6 34. Bb6 (34. Qd3 {is subtle but very effective, lining up against the hanging Bd6.} Qg5 35. Bc5 Rxc7 36. Qxd6 $18) 34... Qe4 35. Qa6 Rg8 {my opponent had obviously missed this mate threat, by his reaction. This is defense by swindle threat.} 36. Qf1 (36. Kf1 {is what the computer recommends, but it is psychologically difficult for a human under pressure to play.} Qxg2+ 37. Ke2 $18 Bg3 38. Rf1 {and White holds, with Black having to lose material to stop the pawn promotion.}) 36... Qb7 (36... b3 { immediately is what Houdini prefers, but I was under some time pressure and wanted to have a lock on c8 first.} 37. f3 Qb7 38. Qd3 $16) 37. Bxa5 (37. g3 $5 {would remove the mate threat on g2.} Qxb6 38. c8=Q Rxc8 39. Rxc8 $18) 37... b3 $16 38. Rb1 Bxc7 {this unnecessarily loses a pawn.} (38... Qd5) 39. Bxc7 Qxc7 40. Rxb3 $18 {now it's hard to see White being unable to win, with the position simplified.} Qc6 {with the idea of keeping the threat against g2 active.} 41. Rb5 (41. a4 Rg5 42. Rb5 Rg8 $18) 41... Qe4 $2 {this misses a very useful deflection tactic:} (41... Rxg2+ 42. Qxg2 Qxb5 $16 {and this is now, in practical terms, a difficult endgame for White to win at the Class level.}) 42. a4 $18 Rd8 {by this point it was late in the evening and I had stopped checking for my opponent's threats, missing his next move.} (42... Qc6 43. f3 Rc8 44. a5 $18) 43. Qe2 {now the h-pawn will fall to White's queen and Black's position along with it. I could have resigned here.} f5 44. Qxh5+ Kf6 45. Qh6+ Ke7 46. Qg7+ (46. Qg7+ Ke8 47. Rb7 Qxb7 48. Qxb7 $18) 1-0