Classical Variation

From c5 the bishop eyes g1, so White cannot castle short and d4 is hard to arrange for the moment. The bishop is irritating enough that White often spends two tempi on Nc3–a4 to exchange it on c5 or b6. The position also arises by transposition from the Vienna Game or Bishop's Opening when f4 comes before Nf3. Engines rate it as roughly balanced. In practice 3. Nf3 is played in the vast majority of games, while the greedy 3. fxe5 scores poorly for White. The alternative 3. Bc4 is answered well by 3...d5 4. Bxd5 Nf6.

After 3. Nf3, 3...exf4 is considered inaccurate because 4. d4 gains time on the bishop, and the usual reply is 3...d6. White then chooses between 4. c3, preparing d4 for a broad center, 4. Bc4 and 4. Nc3. Against 4. c3, Black can hit back with the Rubinstein Countergambit, 4...f5, or pin with 4...Bg4, after which 5. fxe5 dxe5 6. Qa4+ is the Euwe Attack. The Rotlewi Countergambit, 4. b4, sacrifices a pawn in the manner of the Evans Gambit to build a center with c3 and d4, but is regarded as slightly dubious. The Walthoffen Attack, 3. Qh5, is a rare deviation.