Chess Opening Theory/1. e4/1...e5/2. Nf3/2...f5/3. Nxe5/3...Qf6/4. Nc4/4...fxe4/5. Nc3/5...Qf7

= Latvian Gambit, Leonhardt Variation =

5...Qf7
Black is planning ...d5 again. Now comes perhaps the only "unnatural" move with which a White player facing the Latvian must be familiar: /6. Ne3/. There's no other way to defend against ...d5.