Tout ou rien

Jean Fricker – Roberto Cosulich
17th International Festival; La Spezia, March 1970
Dutch Defence A89

1. Nf3 f5 2. c4 Nf6 3. g3 g6 4. Bg2 Bg7 5. 0-0 d6 6. d4 0-0 7. Nc3 Nc6. The Matulović Variation of the Leningrad Dutch.
8. d5 Na5 9. Qd3 c5. If 9. ... e5 then 10. dxe6 Bxe6 11. b3⩲ (an assessment by none other than Botvinnik).
10. Rb1!? (10. b3)
10. ... Ne4! 11. Nb5?! If 11. Nxe4 fxe4 12. Qxe4 then 12. ... Bf5 skewers Queen and Rook. Best is probably 11. Ng5 Nxc3 (11. ... Nxg5 12. Bxg5⩲) 12. bxc3 Qe8! (Δ ... Qe8-a4) 13. Rb5 b6 (Fauland – M. S. Tseitlin, 15th “Dezső Elekes Memorial” International Tournament, Budapest 1990) and now, according to Tseitlin himself, 14. Ne6 should give White the advantage.
11. ... a6 12. Na3

12. ... b5! 13. Nd2 13. cxb5 axb5 14. Nxb5 Ba6 gives Black at least enough compensation for the Pawn, pretty similarly to the way it goes in the Benkö Counter-Gambit.
13. ... Rb8! 14. Nxe4 fxe4 15. Bxe4 Nxc4 16. Nxc4 bxc4 17. Qc2. Obviously not 17. Qxc4 because of 17. ... Rb4−+ 18. Qc2 Rxe4 19. Qxe4 Bf5 skewering Queen and Rook.
17. ... Qa5 18. h4? Here White, labouring under the false impression that he has a mating attack, burned all bridges behind him. He should have played 18. Bg5 Rb7 19. a3 with a still tenable position.
18. ... Qxa2 19. h5 Bf5 20. hxg6 hxg6 21. g4!? The point of White’s play, but he overlooked something important.
21. ... Bxg4 22. Bxg6. With the winning threat of Qc2-e4.

22. ... Qb3! 23. Qe4 Qh3! That’s all! And now it is Black who threatens a mate by ... Rb8-b3-g3+.
24. Bg5 Bf5! Cosulich plays it simply.
25. Bxf5 Rxf5 26. Qh4. Losing a second Pawn, but no better is 26. Bxe7 Re5 27. Qh4 Qf5!, for if 28. Bxd6 then 28. ... Qg6+ winning the Bishop.
26. ... Qxh4 27. Bxh4 Rxd5 28. e3 Bxb2 29. Bxe7 Kf7 30. Bh4 c3 31. e4 Rh5 0–1.