The challenge in using Greco’s mate, as with the others, is to get the needed lines open. Here White has a bishop trained on g8 and realizes he could mate by adding pressure down the h-file. How to get the file open? By requiring Black's h7 pawn to capture. It doesn’t protect anything that White can take, but it does guard a square from which White can give check: he plays Ng6+ and the reply h7xN is forced; now Rh1 mates by adding the familiar pressure down the h-file. Knight sacrifices to open the h-file are a common feature of Greco’s mate.