Endgame of the Week: King and Pawn vs. King on the a-file or h-file
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A rook pawn (on the a-file or h-file) has much less chance of promoting than other pawns. The reason is that if the opposing king can get to any square in front of the pawn, it can not be driven away from the file, and the pawn can not queen. Black can always draw if he can reach the c8 square for an a-pawn (pawn on the a file) or the equivalent f8 for an h-pawn, except for the position in the next diagram, with White to move. Therefore, an advanced rook pawn generally has two key squares: b7 and b8 for an a-pawn, and g7 and g8 for an h-pawn. The key squares are indicated by the black dots in the position in the diagram on the right:
If White's king can reach either of the two key squares, he can keep Black's king away and the pawn will promote. If the Black king can reach any of the squares marked with a dot or an "X", it stops the pawn (Silman 2007:105-6).
The pawn can also promote in the position on the right (if White is to move), after
- 1. h7
However, in practice most of the time the black king can stop a rook pawn because it is usually close enough that the white king can not prevent it from getting in front of the pawn (or capturing it).
[edit] Example from game
In this 1968 game between Oscar Panno and Miguel Najdorf,[1] continued
- 59. Kg4 Kc7
- 60. Kg5
and White won because the white king can reach the key square of g7. Black resigned in light of
- 60... Kd7
- 61. Kg6 Ke7 (if 61... Ke6 then 62. h4, not 62. Kg7?? because 62... Kf5! wins the pawn)
- 62. Kg7 (moving to a key square, the only move to win) Ke6
- 63. h4 (the only move to win) Kf5
- 64. h5 (the only move to win)
and the king protects the pawn as it promotes.
If Black was to move in this position, he would draw by reaching the f8 square and preventing the white king from getting to a key square, and the pawn cannot promote (Müller & Lamprecht 2007:22).
