Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bc4/3...Nf6/4. Ng5/4...Bc5/5. Bxf7/5...Ke7/6. Bd5/6...Rf8/7. Bxc6/7...dxc6/8. d3/8...Ng4/9. Nh3

=Traxler Counterattack=

9. Nh3. Not only defending the f2 square but emptying the g5 square and thus threatening the aggressive Bg5 move.

Theory table
.
 * 1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 Bc5 5. Bxf7+ Ke7 6. Bd5 Rf8 7. Bxc6 dxc6 8. d3 Ng4