Aljechin, Alexander - Shishkov, Viktor; 1919

Hi, guys,

I found this part of a game in the SCID tactics database as a puzzle to solve.

Chess.com won't accept the game otherwise:

[FEN "8/8/5pkp/P2R1p2/8/3P2p1/5qP1/5R1K w - - 0 1"]

1.Rxf2 gxf2 2.Rxf5 Kxf5 3.g4+ Ke6 4.Kg2 Kd6 5.Kxf2 Kc6 6.Ke3 1-0

After 3. g4+ the black king moves away instead of capturing the pawn. Why is that?

To my understanding, the king should capture the pawn: 3. g4+ Kxg4

When I analyze this, e.g. using Stockfish 14, it also flees the pawn. Can someone, please, enlighten me? Is there a chess rule I don't know about? What is the deeper meaning of moving the king away?

Thx a lot!

PS: I cannot insert my PGN data using the board symbol although everything seems okay...

You're right, after check, the best thing is to capture the pawn, but white will win anyway. If you capture the pawn, it will only take a little longer.

Stockfish development version 22032822 (March 28, 2022 at 10pm) already suggests capturing.

I posted a video on my Youtube channel today if you want to see it. The channel is Xadrez para Mortais, and the title of the video is Encontre o melhor lance – 013. It's in Portuguese, but it's very easy to understand!

Encontre o melhor lance – 013 at Xadrez para Mortais

Thank you for your answer! - After posting my question I have done some research using Deep Shredder 13 and Stockfish 14, and so I eventually understood that there is nothing black can do. As you say, white will win in every case. 

I'll watch your video asap, thanks for the hint!