4.exf5?! e4 5.Bd2 exf3+ 6.Bxf3 gxf5 , when the connected pawns and the strong bishop on g7 yield Black some slight compensation for the piece.
A decisive queen transfer with two concrete ideas: 2 R(Q)h3 with mating motifs, and 2 Qg2, creating deadly threats at g7 and g8.
After 2...Qg2 , due to the double threat of 3.Rg8+ and 3.Rh3! Qxh3 4.Qg7# Black resigned.