Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nc6/3. Bc4/3...Nf6/4. Ng5/4...d5/5. exd5/5...Na5/6. Bb5/6...c6/7. dxc6/7...bxc6/8. Qf3/8...Rb8/9. Bd3

= Two Knights:Colman Defence =

9. Bd3
This Bishop retreat while unnatural due to it blocking in the d-pawn gives added protection of the e4 square which the White Knight may soon occupy makes this a tough move for Black to face.

Theory table
.
 * 1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 d5 5.exd5 Na5 6.Bb5+ c6 7. dxc6 bxc6 8. Qf3 Rb8 9.Bd3

Statistics
Estimated next move likelihood h6 50%, Bd6 30%, Be7 20%