Classical Variation

The idea

This is the main line. White takes the pawn with 3.Nxe5, Black drives the knight back with 3...d6, and after 4.Nf3 Nxe4 material is level and the position symmetrical again.

The big question for White at move 5 is how to deal with Black's knight on e4: support d4 and attack it with 5.d4 and 6.Bd3, or trade it with 5.Nc3.

Plans for White

Play 5.d4, then 6.Bd3 to challenge the knight on e4 and prepare castling. Or play 5.Nc3, the Nimzowitsch Attack, which trades the knights, doubles White's c-pawns and leads to a sharper game with castling on opposite sides.

Either way, White's extra tempo and slightly freer pieces are the trumps; play for small advantages.

Plans for Black

Keep the knight on e4 supported with ...d5, and finish development with ...Be7 or ...Bd6, ...Nc6 and ...O-O. Black's position is very solid, so be patient: there is no need to force anything.

Watch out for

For Black, the early pin on the e-file. With White's queen able to reach e2 and Black's king still on e8, a knight on e4 can be pinned. In the Nimzowitsch Attack, 5.Nc3 Bf5?? 6.Qe2 wins a piece (see that page).

For White, forgetting to retreat. 4.Nf3 is the main move: 4.Nxf7 is the Cochrane Gambit, which gives up the knight for a pawn and Black's right to castle.