Fundamentals (part three)

Spanton (164) - D Moskovic (118)
Barbican Rapidplay 1989

Queens have just been exchanged on g2 - who stands better?

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White has a farside pawn-majority and can hope to create a passed pawn there by sacrificing the c pawn. But this is a faint hope as both kings have to be correctly placed, from White's viewpoint, for this to work.
Black has a protected passed pawn, but it seems, at least at first glance, that White can stop the black king from reaching g5, where it could support the pawn's advance. In fact White cannot stop ...Kg6-g5, at least not without losing the game, but the black king getting to g5 is not as threatening as might be thought.
So the position is drawn with correct play, but it contains some deep subtleties.
31.... Kg6 32.Kg3
Not 32.h4?, but can you see why?
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After 32.h4?, Black can try 32...Kh5, but on 33.Kg3 he has to accept a draw as 33...f4+?, to create a passed h pawn, loses to 34.Kxf4 Kxh4 35.c4! etc.
But the analysis engines Stockfish10 and Komodo10 give 32...a5!, when White is completely lost. There are two main lines: a) 33.Kg3 b4 34.cxb4 axb4 35.Kh3 Kh5 36.Kg3 f4+! 37.Kxf4 Kxh4, when the black h pawn decides the game, eg 38.Ke3 Kg4 39.Kd2 h5 40.a4 bxa3 41.Kc2 h4 etc; b) 33.b4 axb4 34.cxb4 f4 (34...Kh5 also wins) 35.Kf3 Kf5 36.a3 h5, and White is in zugzwang.
32...Kg5 33.a3 f4+
White to play and draw.
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34.Kf3?
34.Kf2 and 34.Kg2 draw. The point is to meet 34...Kf5 with 35.Kf3, when White holds after, say, 35...a5 (35...h5? loses to 36.h4, when the f pawn will eventually fall) 36.a4 bxa4 37.bxa4 Kg5 (...h5? again loses to h4) 38.Kf2 Kh4 39.Kf3 Kg5 - neither side can make progress as 39...Kxh3? loses to 40.Kxf4 and 41.c4!
If, after 34.Kf2/g2, Black plays 34...Kh4, then 35.Kf3 forces the black king back to g5 as 35...Kxh3? loses to 36.c4! or to 36.Kxf4 with c4! to come.
34...Kh4??
This seems to turn a win into a loss. Correct is 34...Kf5, when White's best appears to be 35.b4 Kg5 36.Kf2 Kh4 37.Kf3 Kxh3 38.Kxf4 h5 (not 38...Kh4? 39.c4! bxc4 40.a4 etc) 39.Kg5 (now 39.c4? bxc4 40.a4 does not work as Black has 40...Kg2 41.b5 axb5 42.axb5 Kf2! 43.b6 c3 44.b7 c2 48.b8=Q c1=Q#) 39.Kg5 h4 40.Kf6 Kg2 41.Kxe6 h3 42.Kd7 h2 43.e6 h1=Q 44.e7 Qh3+ 45.Kd8 Qxc3 46.e8=Q Qxd4. After the engines' long, but mostly forced, line, Black emerges a passed pawn up in a queen-and-pawn ending, and presumably should win, but there is a lot of play left.
35.Kxf4 Kxh3 36.c4!
Black is lost. The game continued …
36...bxc4 37.bxc4 dxc4 38.d5 c3 39.Ke3
...and White won.