Fundamentals (part 46)

Dominic Klingher (2116) - Spanton (1927)
Jersey 2017

Black has just captured on g7 - who stands better?

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White is winning because the passed g pawn can be used to distract the black king from the queenside. Meanwhile it will not be easy for Black to create a passer.
40.Kf2 Kf6 41.Ke3 Ke5
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42.g4?
Premature. White should improve his position on the queenside before pushing the g pawn. The analysis engines Komodo11.01 and Stockfish11 give 42.a4 as best, eg 42...a6 and only now 43.g4 when 43...a5 (43...b5 44.a5 is no improvement) 44.Kd3 leaves Black in zugzwang.
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42...b5!
The only drawing move.
43.g5
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43...Kf5?
Black again had to find an only move, viz 43...a6, eg 44.g6 Kf6 45.Kd4 Kxg6 46.Kxd5 Kf5 47.Kc5 Ke4 48.Kb6 Kd5! 49.Kxa6 Kc5 50.a3 Kc6! 51.Ka5 Kc4 when White cannot make progress.
44.Kd4 Kxg5 45.Kxd5 Kf4 46.Kc5 a6 47.Kb6 Ke4 48.Kxa6 Kd3 49.Kxb5 Kxc3 50.a4 1-0