1. Qg3! attacks the defender of the d8-Rook and at the same time threatens Qxc7 and Qxg6+
1. Qg3 Qxg3 2. Rxd8+, followed by fxg3 wins material.
Note: This combination works only because 2. Rxd8+ is check. Black has to deal with the check first and only then does white play fxg3.