Romeo and Juliet

Heinz Schaufelberger – Roberto Cosulich
2nd International Festival; Verona, April 1976
Queen’s Indian Defence E14

1. d4 Nf6 2. Nf3 e6 3. c4 b6 4. e3 Bb7 5. Bd3 Be7 6. 0-0 0-0 7. b3 d5 8. Bb2 dxc4 9. bxc4 c5 10. Nbd2 Nc6 11. Qe2 Qc7 12. Rfd1 Rfd8 13. Rac1 Rac8 14. Bb1 cxd4 15. exd4 Qf4 16. Ne4. International Master Dieter Keller, in his comments for Neue Zürcher Zeitung, No. 123, May 28, 1976, p. 77, suggested 16. Nf1 as better, preventing Black from playing ... Nc6xd4.
16. ... Nxe4. Critical is 16. ... Nxd4 17. Nxd4 Nxe4 18. g3 Qxf2+! (obviously, 18. ... Qe5?? 19. Nc6 loses on the spot) 19. Qxf2 Nxf2 20. Kxf2 Bg5! with unclear but balanced play.
17. Bxe4 Bf6 18. g3 Qg4 19. d5

19. ... Bxb2? This is the decisive mistake. Black should have played 19. ... exd5 20. cxd5 (20. Bxf6 Re8! 21. cxd5 Rxe4 is good for Black) 20. ... Ne5! which, apparently, holds everything together.
20. dxc6 Bxc6. If 20. ... Bxc1 then 21. cxb7 Rxd1+ 22. Qxd1 Rb8 23. Qd7 winning at once.
21. Rxd8+ Rxd8 22. Rd1 Rxd1+ 23. Qxd1. The back-rank mate threats give White easy ways to win the day.
23. ... Bd5! An ingenious trick that at least saves the piece, if not the game.

24. Qa4! Just so. 24. cxd5? Qxe4 25. dxe6 Bf6 26. Qd6 fxe6! 27. Qb8+ Kf7 28. Qxa7+ Kg6 would leave White empty handed.
24. .. b5 25. Qxb5 Ba3 26. Bxd5 exd5 27. Qxd5. Threatening Qd5xf7+. Whether or not Black exchanges Queens, White’s extra Pawn and initiative would win easily in the endgame.
27. ... Qc8 28. Ne5 Qf8 29. Kg2 g6 30. h3 Qe7 31. Nc6 Qb7 32. Qd8+ Kg7 33. Qd4+ Kg8 34. Qd5 Bf8 35. a4 Qb6 36. Ne5 Qc7 37. Nd7 Be7 38. c5 Qd8 39. c6 1–0.