Mate in 2

The g5 pawn is pinned, so if Black plays 1...h4, White can respond with 2.Rxh4, a neat little pin-mate. However, in the current position, White has no immediate mating reply if Black simply shifts the rook from g6—their only other legal option.

What can White play to prepare for a random move of the rook on g6, while still keeping 2.Rxh4# available against 1...h4? The key is the quiet, sacrificial 1.Rg4!—the only move that covers all bases. Black is now in a zugzwang. 1...R-any is met with 2.Qxg5#, while 1...h4 still runs into 2.Rxh4#. And finally, after 1...hxg4, White has 2.Qh2#.