Editing Two Knights Defense (section)

====4...Nxe4====
4...Nxe4?! is considered unsound but must be handled carefully. 5.Nxe4 d5 poses no problems for Black. If 5.Nxf7? Qh4! 6.g3 (6.0-0 Bc5!) 6...Qh3 7.Nxh8 Qg2 8.Rf1 Nd4 9.Qh5+ g6 10.Nxg6 hxg6 11.Qxg6+ Kd8 and Black has dangerous threats.<ref name=Harding1977>Harding & Botterill (1977), p. 66</ref> (Alternatively, after 5.Nxf7? Qh4! 6.g3, Black could play more aggressively 6...Nxg3! 7.fxg3 Qe4+ 8.Qe2 Qxh1+ 9.Qf1 Qxf1+ 10.Kxf1 d5 11.Bxd5 Bh3+ 12.Ke1 Nb4 13.Bb3 Nxc2+ 14.Bxc2 Kxf7 with a distinct advantage of material for Black.)
Correct is 5.Bxf7+! Ke7 6.d4! (6.d3 is also good) and now:
* 6...d5 7.Nc3! (best, discovered by Soviet player Lopukhin; White has a clear advantage) 7...Nxc3 8.bxc3 Qd6 (8...Bf5 9.Qf3{{chesspunc|±}}; 8...e4 9.f3!) 9.a4! Kd8 10.Bg8! Ke8 11.Bxh7± (Estrin).<ref name=Estrin1971>Estrin (1971), p. 67</ref><ref name=Harding1977 />
* 6...h6 7.Nxe4 Kxf7 and now 8.dxe5 Qe8 9.f4 d6 10.0-0 ({{chesspunc|±}}) Kg8 11.Nbc3 dxe5 12. f5 Qf7 13.Nd5 Bd7 14.f6 g6 15.Ne7+! and White has excellent chances (Estrin).<ref name=Estrin1971 /><ref name=Harding1977 />