Spotting Tactical Threats
Seirawan Strategy Example #1
Winning Chess Strategies, Diagram 10, p34
In this example, White threatens to capture Black's Queen with the Rf7. While Black's King could then capture White's Rook, it wouldn't be sufficient to prevent White from losing his two Passed Pawns (a3 & b4).
Black spots this Tactical Threat and deals with it, ruthlessly sacrificing his Queen in order to preserve his Promotion-chasing Pawns ...