Chess Opening Theory/1. e4/1...e5/2. Nf3/2...Nf6/3. Nxe5/3...Nxe4

A sideline. Black takes back on e4 immediately, but despite appearances, Black doesn't get to keep material equality this way. With best play for Black this line is a pawn sacrifice for which Black obtains some compensation.

4. Qe2 attacks the knight and sets up discoveries along the e-file that Black has opened. Black's best move is 4...Qe7, setting up a pin of their own after after 5. Qxe4. This leads to the Kholmov gambit: 5...d6 6. d4 dxe5 7. dxe5 Nc6⩲ and Black wins the piece back at the cost of the d-pawn.

4. Qf3?! may be played, hoping for Black to defend their knight 4...d5?? 5. Qxf2# instead of 4...Nf6 or 4...Ng5.

4. d4 may transpose into a Classical attack after 4...d6 5. Nf3.

This line was introduced by Pedro Damiano in his book, Libro da Imparare a Giocare a Scacchi (Italian: Book for learning to play chess), one of the oldest books on "modern rules" chess. Damiano gives 1. e4 e5 2. Nf3 Nf6 3. Nxe5 Nxe4 4. Qe2 Qe7 (this is now known as the Kholmov gambit) 5. Qxe4 d6 6. d4 f6 7. f4 dxe5 8. dxe5 Nd7 9. Nc3 fxe5 10. Nd5 Qd6(??. 10...Nf6 is better) 11. fxe5 Qc6 12. Bb5 Qc5 13. Be3 to trap the queen.^[1]

1. e4 e5 2. Nf3 Nf6 3. Nxe5 Nxe4

Wikipedia has related information at Petrovs Defence.

• Kasparov, Garry, & Keene, Raymond 1989 Batsford chess openings 2. ISBN 0-8050-3409-9.