TCEC Season 13 Superfinal Game 75 – Stockfish-Komodo
|Game||Season 13, Superfinal, Game 75|
|Links|| TCEC archive|
Stockfish (playing as white) faced Komodo in a tactical opening of Italian Game, Two Knights Defense, Steinitz Variation (C59). With a spectacular temporary piece sacrifice, black created a strong passed pawn. Despite still being pawn down after the recapture, black was able to use the threat of the passed pawn and white's lack of king-side development to overload white's defenses. This won black another passed pawn and the game.
|Position after 23. Qc3|
1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. Ng5 d5 5. exd5 Na5 6. Bb5+ c6 7. dxc6 bxc6 8. Be2 h6 9. Nh3 g5
10. Nc3 Nb7
Novelty by the Lichess masters database.
11. Ng1 Bc5 12. Kf1 Be6 13. d3 Qc7 14. Rb1 O-O-O 15. Qe1 Bb6 16. b4 Nd6 17. Na4 Rhe8 18. Bb2 Bf5 19. Rd1 Bd4 20. c3 Bb6 21. Nxb6+ axb6 22. c4 Rd7 23. Qc3 (diagram)
The critical position of the game. Black offers a temporary piece sacrifice by pushing the e-pawn and white obliges. The underlying tactics are quite complicated, but it seems that the temporary piece sacrifice is solid if not winning. See Editor's notes below.
|Position after 44... Rd8|
23... e4 24. Qxf6 exd3 25. Bf3 Re6 26. Qd4 Ne8 27. Qc3 g4 28. h3 gxf3 29. Nxf3
Now black got the piece back, but is still a pawn down. However, the strong d-pawn is more than enough compensation.
29... Be4 30. Bc1 c5 31. bxc5 Qxc5 32. Ne1 b5 33. Be3 Qxc4 34. Qd2 Qd5 35. Qc3+ Rc6 36. Qb3 Nc7
While being pawn up, white is starting to become overloaded. Note that 37. Qxd5 is not a working option, because black would be able to create another passed pawn. For example: 37. Qxd5 Nxd5 38. Nf3 b4 39. Ne5 Nxe3+ 40. fxe3 Rc2 41. Nxd7 Kxd7. Now the threat of Rxa2 and then pushing the b-pawn is winning, even after giving up the exchange.
37. Qb2 Qc4 38. Kg1 Nd5 39. Kh2 Nxe3 40. fxe3 f5 41. Rg1 Qa4 42. Qa1 Kb7 43. a3 Rg6 44. Qc1 Rd8 (diagram)
White has now ran out of good defensive options and gives up the pawn on a3. This gives another passed pawn for black. For example:
- 45. Rd2 Qa7 46. Rb2 Qb8+ 47. g3 Qe5 48. a4 Rc6 49. Qa1 Qc3 50. axb5 Rcd6 51. Ra2 Qxa1 52. Rxa1 d2 and the d-pawn queens by force.
- 45. Rf1 Rc8 46. Qd2 Qxa3 and the game would transpose close to the game continuation.
- Being passive would not work either: 45. Kh1 Qc4 46. Qd2 Rdg8 47. Rb1 Rg3 48. Rf1 Ka6 49. Rb4 Rxg2 50. Nxg2 Rxg2 51. Rxc4 Rxd2+ 52. Rxe4 fxe4 and black has easily winning rook-pawn endgame.
|Position after 51... Qc3|
45. Qd2 Qxa3 46. Rf1 Rc6 47. Qf2 Rg8 48. g3 Rgc8 49. h4 Rc2 50. Nxc2 Rxc2 51. Rd2 Qc3 0-1 (diagram)
The game was adjudicated as win for black by the TCEC win rule.
The b-pawn is now winning for black. For example:
- 52. Rxc2 dxc2 53. Rc1 b4 54. Qf1 b3 55. Qb5+ Kc7 56. Kh3 b2 57. Rxc2 Bxc2 58. Qe8 b1=Q
- 52. Rfd1 b4 53. Qe1 b3 54. h5 b2 55. Kh3 Rxd2 56. Rxd2 Qxd2 57. Qxd2 b1=Q
The position after 23. Qc3 is complicated even for a more recent Stockfish (sf-dev 2019-09-25 commit 0436f01d). Only after 235 Gnodes, SF-dev was finally able to find 23... e4 as the best move for black on my machine with multi-PV 4. Arguably, the reason why this position is so difficult to evaluate is that the position is rich with deep tactical lines including zwischenzugs, which complicate the search.
Possibly the most problematic search line was 23... e4 24. Qxf6 24... exd3 25. Bh5. However, that eventually fails for complicated tactics initiated by 25... Qa7. For example: 25. Bh5 Qa7 26. Bf3 Qa4 27. Qc3 Re2 28. Nxe2 Qxd1+ 29. Qe1 Qc2 30. Qc3 Nxc4 31. Qxc2 dxc2 32. g4 Bd3 33. Bc1 Ne5 34. Kg2 Bc4 35. Nc3 Nxf3 36. Kxf3 Rd3+ 37. Be3 Rxc3, and only now black gets the piece back. This exact line is not forced by any means, but it gives an idea of the complexity of the position.
- https://lichess.org/191Y9FZ8#19 (Accessed on 2019-09-29)