The Mindsports Masters GM Norm event in London in September produced the following interesting position early on:
46. ?
If you would like to treat this as a (not too easy) puzzle, please don’t read further.
David Fitzsimons now erred with 46. Qb8+?. The right way is 46. a7!, which wins after 47… e2 48. a8=Q+ Kh7 49. Nf7!, e.g., 49… e1=Q (else White can prevent this promotion) 50. Qh8+ Kg6 51. Rg4+ and White mates in a few more moves.
After the game’s 46… Kh7 47. a7 e2, 48. a1=Q? was another error, and after 48… e1=Q, White was lost. More often than not, the side promoting first wins in these four queens games, but here White runs out of checks quickly.
Instead, there was still a (difficult) draw to be had via 48. Nf7!!. The rook capture loses, while the queen capture and the immediate promotion only draw.
[Click to replay the full game.]
Why does this startling knight move work? One hint lies in the fact that the position after the game’s 48… e1=Q, easily won for Black, would instead be convincingly won for White if only the knight were not on the board. After 49. Qg8+ Kg6, White’s 50. Qxc6 would be a devastating check if it were not for the knight. Thus 49. Nf7 is (partly) a line-opening sacrifice.