Figure 5.3.2.4[White to move]

White attacks nothing as yet, but he does see that the knight on f6 is protected only by its king. This alone is suggestive, so he experiments with any checks he can give. There is just one: Qe7+. It attacks the knight and checks the king, forcing it away to the eighth rank or to h6. Now White wins the knight with QxN. The key: remember that any piece drawing protection from its king is a potential target, whether or not it currently is under attack; simple checks may leave it loose.