Figure[White to move]

Again you see White’s queen and another piece (his bishop) ready to pounce on a square next to Black’s king, this time deterred only by the protection Black’s queen supplies to f7. On this abbreviated board there is no way to get at the Black queen directly. But a glance at its route to the mating square reveals a way to obstruct it: 1. Rf6. Again the rook has protection against the simple QxR, which otherwise would renew the Black queen’s protection of the square; and Black’s queen has no safe place it can go to protect it. The best Black can do is 1. …Qe6; 2. Qc5+, Re7 (interposing). (If Black plays 2. …Qe7, interposing his queen, White has 3. Rxf7+ and 4. RxQ.) Assuming Black sticks with Re7, play might go 3. RxQ, g7-g6, 4. Qc8+, Kg7; 5. Ra6, Rxe5; 6. Ra8, g6xB; 7. Qh8+, Kg6; 8. QxR, where White wins a queen and a rook for a bishop and a pawn. Anything less precise by Black is liable to get him mated. But the important thing to see here is the basic idea of 1. Rf6.