Modern Defense

With 3...d5, also known as the Abbazia Defense, Black hits the e4-pawn and opens the c8-bishop. Unlike 3...d6, the move threatens ...dxe4 at once, so White usually spends the tempo on 4. exd5 rather than on development. Black is not trying to keep the extra pawn and plays instead for piece activity and the initiative. The idea is close to the Falkbeer Countergambit, and the position also arises from 2...d5 3. exd5 exf4 4. Nf3. It is often recommended as a simple route to equality, but theory holds that White's extra central pawn and freer pieces give a slight edge. Engines rate it roughly level, and White scores somewhat better in practice.

The main line is 4. exd5 Nf6, attacking d5. White often replies 5. Bb5+, and 5...c6 6. dxc6 bxc6 7. Bc4 Nd5 is the Botvinnik Variation. White can also protect the pawn with 5. c4, 5. Bc4 or 5. Nc3. Instead of 4...Nf6, Black has 4...Qxd5, with a Scandinavian-like position, as well as 4...Bd6 and 4...c6. The second most common reply, 4. e5, is considered inferior. After 4...g5 5. h4 g4 the e5-square is no longer available to the knight, and play can transpose to the dubious Allgaier Gambit.