|Jan-09-13|| ||ozmikey: It's a pity that both Nimzovich and Tartakower (in his book of best games) pass over 28...a5 fairly superficially, when actually it opened up the prospect of an intriguing pawn ending. Tartakower mentions that 29. Qxa5 is met by 29...Qc2+ 30. Kf3 Qxb2, with the c-pawn ready to roll. But what happens after 31. Qd8+ Kg7 32. Qd4+ Qxd4 33. exd4?|
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This ending is by no means as simple as it looks. Black's primary aim must obviously be to bring his king up to attack the d-pawn and then force zugzwang, but this isn't easy. After the obvious 33...f5, to keep the White king out of e4 (and, more generally, limit his/its mobility), White is basically reduced to shuffling his king around, since he doesn't want to "lose" any pawn moves on the kingside (which would give Black a lead in the zugzwang stakes), and g4 at any stage would lose immediately, because Black would then create a passed h-pawn (White couldn't recapture the pawn on g4 with his king, since then the king would be outside the square for the pawn on c4).
So then, after 33...f5, a sample line would be 34. Ke3 Kf6 35. Ke2 Ke6 36. Kd2 Kd5 37. Ke3. Incidentally, 35. d5 is no good because then, after the inevitable match-up of kings on d4 and d6 either side of the pawn, Black triangulates his way to zugzwang (d7-e7-d6) because White only has the e3 square available; again, he can't jump in to e5 as this would set the c-pawn running.
Back to the position after 37. Ke3:
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At first glance it looks like 37...c3 will be enough, after 38. Kd3 c2 39. Kxc2 Kxd4 and Black's in. But then comes 40. Kb3! and White's threats on the queen-side force the Black king to head back, after which neither side can make progress.
Zugzwang, of course, won't work: 37...h6 38. h4! and Black's stuck. So it's a draw after all? No, there's a win here, and a very pretty one it is.
After 37...g5!! White has no defence. To take the simple line first: after 38. g3 gxf4+ 39. gxf4 h6! Black DOES get zugzwang on the king-side, after which d4 drops off and Black wins.
And if Black takes the pawn? 38. fxg5 f4+! (the point!) and if 39. Kxf4 Kxd4 the c-pawn touches down, and White's pawns aren't fast enough. Black can play 39. Kd2 instead, but after 39...Kxd4 40. h4 Ke5 41. h5 Kf5 42. g6 hxg6 43. h6 Kf6, Black is just in time to stop the White pawns, and his own pawns carry the day.
A fascinating endgame. I wonder whether Tartakower had considered any of the difficulties of it when playing 28...a5.