Two Knights Defense, Ponziani-Steinitz Gambit

The Ponziani-Steinitz Gambit answers the Knight Attack by ignoring the threat to f7 and taking the e4-pawn. The idea borrows from the center fork trick. If White recaptures with 5. Nxe4, then 5...d5 attacks both the knight and the bishop and regains the piece with a comfortable game. The flaw is that f7 is now left without support. After 5. Bxf7+ Ke7 6. d4, the king is stranded in the center, and 6...Nxg5 fails to 7. Bxg5+, which also wins the queen on d8. The engine gives White a large advantage, and White scores well with the bishop check in practice.

The knight capture 5. Nxf7 is the most frequent reply in online games but is considered a mistake. Black answers 5...Qh4, using the queen's open path to h4 to attack f2 while White's knight is far from home, and gains the advantage even against accurate defense. Black scores well after this move, which largely explains Black's good overall results despite the line's poor theoretical reputation.