Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bc4/3...Nf6/4. d4/4...exd4/5. O-O/5...Nxe4/6. Nc3/6...dxc3/7. Bxf7/7...Kxf7/8. Qd5/8...Kf6/9. Re1

= Nakhmanson Gambit, Kf6 Defence, Rook Attack =

9. Re1
The prospect of White's rook joining the attack should set off alarm bells for Black, and indeed this position with White to play would be mate in 8 starting with Rxe4. More annoyingly, the same move 9...Be7?? that is recommended against 9.Qxe4, fails in comical fashion against the Rxe4 threat: 10.Rxe4 Qe8 (to guard against Rf4 followed by Qf7) 11.Bg5+ Kg6 12.Nh4+ Kh5 13.g4#. Checkmate by five unique pieces!

The e4-knight can't be defended, but Black can threaten to defend it with the accurate 9...Ne7! to ensure that it's a queen and not a rook that captures it.

So Black's responses to both 9. Qxe4 and 9. Re1 entail putting a minor piece on e7, but you have to pick the right one, and if you pick the wrong one you get checkmated. To remember which is which, think: Attack the queen if you can. If the queen's on d5 because White has played Re1, you can attack it with 9...Ne7. If the queen's on e4 because White has played Qxe4, you can't attack it, so play 9...Be7 instead.