of the first move." (Id. p. 25) The ECO also concludes that Black equalises after the alternative 4.Nxe5 Ne6 5.Bc4 Nf6 6.Nc3 Be7 7.0-0 0-0 8.Be3 d6 8.Nd3 Nxe4 10.Nxe4 d5 (Parma). The main line 3...exd4 4.Nxd4 may transpose into this position if Black chooses to play 4...Nxd4. 3...d6? is often regarded as a mistake and an automatic slight advantage for White. While 3...d6 does defend the e5 pawn, it allows White to play 4.d5 and kick out the knight. The resulting line of 4...Nce7 5.c4 Nf6 6.Nc3 Ng6 allows White an imposing center and better chances for winning. Opting to take on e5 still scores poorly for Black, as 4.dxe5 dxe5 5.Qxd8 leaves black in a losing dilemma: either take with the king and forgo castling rights (5...Kxd8) or to take with the c6 knight and lose the e5 pawn (5...Nxd8 6.Nxe5). Chess.com cites a meager 18% win rate for Black's 3...d6 move. 3...f5?! 4.Nxe5 transposes into a line of the dubious Latvian Gambit. After the usual 3...exd4, White can respond with the main line 4.Nxd4 or can play a gambit by offering Black one or two pawns in exchange for rapid . Main variations After 1.e4 e5 2.Nf3 Nc6 3.d4 exd4, the most important continuations are: 4.Nxd4 (Main line) 4...Bc5 (Classical Variation) 4...Nf6 (Schmidt Variation) 4...Qh4 (Steinitz Variation) 4...Qf6 4...Nxd4 4...Bb4+?! 4.Bc4 (Scotch Gambit) 4.c3 (Göring Gambit) 4.Bb5 (Relfsson Gambit) Main line: 4.Nxd4 In the main line after 4.Nxd4, Black has two major options. Either 4...Bc5 or 4...Nf6 offers Black good chances for an equal game. Classical Variation: 4...Bc5 After 4...Bc5 White has 5.Nxc6, 5.Be3, or 5.Nb3. After 5.Nxc6, play almost always continues 5...Qf6 (Black does not lose a piece on c6 because he is threatening mate with 6...Qxf2) 6.Qd2 dxc6 7.Nc3. On 5.Be3 play almost always continues 5...Qf6 6.c3 Nge7 7.Bc4 (as proposed by IM Gary Lane in Winning with the Scotch; several seventh move alternatives for White are possible here, 7.g3 for example) 7...0-0 (7...Ne5 is more often played here. Play usually continues 8.Be2 Qg6 [8...d5 is also possible] 9.0-0. Here, Black has the option of taking the unprotected pawn on e4, but it is considered "poisoned".) 8.0-0 Bb6 where the position is roughly equal. On 5.Nb3 play almost always continues 5...Bb6 6.a4 a6 7.Nc3. Another plan for White is to play 6.Nc3, followed by (in some order) Qe2, Be3, h4 and 0-0-0. Schmidt Variation: 4...Nf6