patzer2: This pretty sicilian (B33) short is number 4475 in Laszlo Polgar's "5334 Problems, Combinations and Games." The strong 13. Bxf6! is featured as a winning combination, under the theme sacrifice on f3/f6, which I am adding to my "demolition of pawn structure" collection.Gruenfeld's opening move blunder was 10...Nxe5?, falling into an opening trap. Grunfeld probably figured on something like 10...Nxe5? 11. Nxe5 d5 12. Nxe5? dxe5 13. Qxd8+ Rxd8 14. Nxc6 bxc6 = with a good game for Black.
Instead, after 10...Nxe5? 11. Nxe5 d5 12. Bg5!!, Galia springs the trap giving Grunfeld an unpleasant surprise. Black is now busted!!
If 12...Bb4+, then 13. c3! f6 14. Bxf6 (14. Qh5+ and 14. cxb4 also win) 14...gxf6 15. Qxd5
is decisive.
If 12...Qc7, then 13. Qxd5! Nb4 14. Ncd6+! Bxd6 15. Qxd6 Nxc2+ 16. Kf1 Qxd6 (16...Qd7? 17. Qxe5+ Kf8 18. Qc5+
; 16...Nxa1?? 17. Qxc7
) 17. Nxd6+ Kd7 18. Rd1
wins with a piece-up advantage.
If 12...Qd7, then 13. Nb6! Qf5 14. Qxd5 Rb8 15. Rd1 f6 (15...Qe6 16. Qxe6
; 15...Bb4+ c3
) 16. g4! Qxg4 16. Bxf6!
gives White a win.
If 12...Be7, then 13. Ned6+! Kf8 (13...Kd7 14. Nxf7 Qg8 15. Qxd5+
; 13. Bxd6 14. Bxd8
) 14. Qxd5
and Black must give up the Queen to stop mate (e.g. 14...Bxd6 15. Bxd8
).
After the thematic 13. Bxf6! (sacrifice on f6) 13...gxf6 14. Qxd5, White has just enough of an advantage to win.
If 14...Qxd5, then 15. Nxf6+! Kf7 16. Nxd5 Rg8 17. 0-0
gives White a winning advantage due to his extra pawns and the "demolished" Black pawn structure.
If 14...Nd4, then 15. 0-0-0 Bh6+ 16. Kb1 Qxd5 17. Nxf6+ Kf8 18. Nxd5 with two pawns up and a "demolished" Black pawn structure is enough for a White win.
If 14...Bb4+, then 15. c3 Qxd5 16. Nxf6+ Kf7 17. Nxd5 Be7 18. b4
is a decisive White advantage.
If 14...Qe7, then 15. Ned6!
wins. And if 14...f5, then 15. Qe6+
is winning.
17. 0-0-0! is a strong followup in this combination. The alternative 17. Nf5+! wins with complications, but is not as quick or decisive. In the final position, after 18. Rxd4! exd4, the deflection move 19. Re1+! forces Black to give up his queen or get mated.