A <DECOY FOR TEMPO> usually involves the sacrifice of some material in order that some other piece can move with <TEMPO (GAIN OF TIME)> by executing some <FORCING MOVE> (usually a check or threat to the queen). The opponent must then meet the threat created by the <FORCING MOVE> and so whatever other threat this move creates cannot -also- be met.

22 f4! is a brilliant <DECOY FOR TEMPO> by Ivanchuk.

Position after 21 ... ♕d8xg5? 22 f3-f4!:

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White's tactical point is that after 22 ... ♕xf4 23 ♖e4,

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White <GAINS TIME> on the <EXPOSED> Black f4-queen to double his rooks on the open e-file against the soon to be <WHOLLY PINNED> Black e5-knight. That is, because of the <PRIMARY THREAT> of 24 ♖e1x♕f4, Black cannot respond to the <SECONDARY THREAT> of 24 ♖a1-e1, doubling rooks on the open e-file. In effect, White gets to lift his e1-rook to e4 in preparation for doubling <FOR FREE (WITH TEMPO)> since Black must meet the threat to his queen.

If Black then saves his <EMBARRASSED> f4-queen with say 23 ... ♕f5, then the sequnce 24 ♖ae1 f6 25 f4 wins the <WHOLLY PINNED> Black e5-knight.

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A magnificent example by Ivanchuk of the lurking tactical danger that exists whenever a minor piece is on an open file. <MINOR PIECES DO NOT BELONG ON OPEN FILES!> They will be <PINNED> against which ever friendly piece is behind them -or- to a mating/checking focal point behind them on their first rank.

Event "?"
Site "?"
Date "2007.03.19"
Round "?"
White "GM_Ivanchuk(B)"
Black "GM_Anand(B)"
Result "1-0"
Opening "Nimzo-Indian: classical, Noa variation, main line, 7.Qc2" ECO "E37"
NIC "NI.23"
Time "09:51:05"
TimeControl "1500+20"

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. Qc2 d5 5. a3 Bxc3+ 6. Qxc3 Ne4 7. Qc2 c5 8. dxc5 Nc6 9. cxd5 exd5 10. Nf3 Bf5 11. b4 d4 12. g4 Bg6 13. Qb2 O-O 14. Bg2 Re8 15. O-O Nc3 16. Re1 h5 17. g5 Be4 18. Bd2 Ne5 19. Bxc3 Bxf3 20. exf3 dxc3 21. Qxc3 Qxg5 22. f4 Qxf4 23. Re4 White wins 1-0