| Alphastar: Found it. The following is taken from Valeri Beim's "How to Calculate Chess Tactics" book: The following example not only comes from a classic game, but is also very little-known, although without doubt the commentary is of the very highest class. It comes from Botvinnik's excellent book "The return match Alekhine-Euwe". This was published in 1939, but only in Russian, and only in a limited edition of 5,000 copies. It has recently been reissued, although again only in small numbers. 
click for larger viewThis position resulted from a serious mistake by Black on his previous move, when he played 22. ..Rd8-e8?. This move deprived his knight of its only retreat-square, thereby setting up the motif for a combination. Trying to realize this motif, Alekhine replied: 23. g4?
Most annotators awarded this move an exclamation mark, and only Botvinnik identified it as a mistake and showed why! He also showed that attempting to prepare this important pawn-thrust by 23. Kh2? is also an error, after which there follows 23. ..h6 24. g3 Qh5 25. g4 Qh4 and now trying to win material by 26. Nf3?! Nxg4+ 27. Kg2 Qh5 28. hxg4 Qxg4+ 29. Kh1 Qh5+ 30. Nh2 Qxe2 31. Rxe2 Nxc4 leads to a better position for black. Botvinnik also gave a classic example of a summary of the positional considerations, which should always precede the search for candidate moves. There is nothing one can add to this summary, and one only needs to learn to apply the same method. The only thing I want to say is that such logical considerations can only be arrived at by a deep and throrough consideration of the position in all its details. It frequently happens that some seemingly insignificant detail turns out to be vitally important. It is impossible to know in advance which detail this might be, and so the initial stidy of the position needs to be scrupulous and not overlook anything. Botvinnik's note was as follows: "The correct move can be found on the basis of the following considerations. In order to trap the black queen on h4, White needs his pawn on g4, his knight on f3, and his h3-pawn defended. ... It is easy to see that ... if White had played 23. Qf1!!, Euwe could have resigned. The point of the move is that after 23. ..h6 (there is nothing better) 24. g3 Qh5 25. g4 Qh4 26. Nf3 ... White wins a tempo and the black queen is trapped." Botvinnik goes on to point out that numerous annotators of this game, including both Alekhine and Euwe themselves(!), all failed to point out 23. Qf1!!. We now return to 23. g4?:
click for larger viewIn the game, in answer to White's incorrect but dangerous-looking thrust, Black failed to find the correct response, which, as Botvinnik again pointed out, was 23. ..h6! (23. ..Qxh3? is bad, because after 24. Rd3 Qh4 25. Kg2 Nxg4 26. Nxg4! Nxc4 27. Rh3 Qd8 28. Reh1 Qd5+ 29. f3 White has a decisive attack). Then 24. Kg2 Nh7 25. f4 Qe7 leads to an unclear position. Instead, Black commited his second successive bad mistake: 23. ..Nc6?
White now won a piece and subsequently, the game. | 
