Alekhine’s Missed Win in Game 23 of the 1937 World Championship rematch - Revealed After 88 Years

The 1937 World Chess Championship rematch between Max Euwe and Alexander Alekhine ranks among the most thoroughly analyzed encounters in chess history. Game 23, played across two sessions on November 30 and December 1 in The Hague, has long been considered a hard-fought draw—an outcome accepted by generations of commentators following tenacious and balanced play by both sides.

However, fresh analysis has uncovered a remarkable missed opportunity: a decisive winning continuation for Alekhine on move 37 involving the previously unnoticed tactical blow 37...f5!. This resource escaped the attention of every major commentator, including Alekhine himself and Euwe (M. Euwe en A. Aljechin, Euwe-Aljechin 1937 - De strijd om het wereldkampioenschap schaken, gespeeld in Nederland in 1937, A.W. Sijthoff, Leiden, 1938, p. 96), Botvinnik (Botvinnik, Alekhine vs. Euwe Return Match 1937, p. 96 of the English 1973 edition), Kasparyan (Shakhmaty v SSSR, n. 3, 1938, p. 119), and many others. The natural-looking sequence 37.Rb5? Kg6? was so universally accepted that even the prominent endgame expert Nikolai Grigoriev (Шахматное творчество Н. Д. Григорьева. Москва 1954, п. 214) and Smyslov and Levenfish (Rook Endings, p. 158 of the 1989 English edition) began his analysis only from move 40, when the adjournment occurred.


No existing commentary identified 37.Rb5? as a losing move, nor did anyone suggest 37...f5! as the key winning idea. Yet after Euwe's seemingly solid 37.Rb5?, Black had a clear path to victory with best play. Alekhine instead played 37...Kg6?, a passive reply that let the win slip away. 

The breakthrough move 37...f5! was the only path to victory - a bold pawn sacrifice that indirectly defends the h5-pawn by tying the white rook to the b-file. By sacrificing the f5-pawn, Black ensures that White’s rook remains tied to the b-pawn. Following up with Rd2, Black activates the rook and centralizes the king without interference. The white king, stuck on the back rank, cannot assist. 

If instead Black tries the immediate sacrifice 37...Kf6, aiming to carry out the plan of placing the pawn on b2 and the rook on d2 to tie down the white king, the idea fails: after the loss of the h5-pawn, White’s passed h-pawn becomes a powerful resource, restricting the Black king and ultimately neutralizing any winning chances.

The only defensive move for White instead of 37.Rb5 was 37.Kf1!, bringing the king into play in time to hold the balance. 

This analysis is a vivid reminder that even the most scrutinized classical games can still hold hidden treasures - waiting to be revealed decades later.