White is nervous; his king is trapped in the corner with Black’s queen and bishop trained on its general position though not perfectly coordinated. Plus White's rook may be lost if he removes his queen’s protection of it. What to do? Look for queen moves that continue to protect the rook and also add pressure against Black. One such move is 1. Qd5, since it not only attacks Black’s bishop while still protecting the rook but also creates the three-piece kernel of a discovered check, enlarging the power of both queen and rook. Indeed, this move wins the game:
(a) If Black plays 1. …Qc1+, hoping to divert White’s energies by taking the offensive, White executes the discovered check with 2. Rf1+, blocking the check against his own king and preparing to take Black’s queen after Black moves his king out of check. (Actually, after 2. Rf1+ it goes 2. …Kg7, 3. QxB+, and then White plays RxQ. Black’s queen will remain en prise to White’s rook so long as White keeps checking Black’s king with his queen and doing other damage with it in the meantime. The priority of check.)
(b) If Black instead plays Qc6 as his initial response, pinning White's queen, he of course loses his own queen to QxQ. Yes, this capture allows Black to play KxR, but then White plays Qd5+ and wins Black’s bishop with a queen fork. White’s queen is the only piece left when the smoke clears.