Abbazia Defense

The Abbazia Defense is the main line of the Modern Defense, 3...d5, and both names are used for the 3...d5 complex. Black gives back material instead of defending the f4-pawn. After 4. exd5 Nf6 the knight attacks d5, and White usually lets Black regain a pawn in exchange for development. The idea resembles the Falkbeer Countergambit, and the position can arise from it via 1. e4 e5 2. f4 d5 3. exd5 exf4 4. Nf3. Black plays for piece activity and the initiative. White hopes that the extra central pawn and active pieces give a small but lasting plus.

In online play 5. c4 is the most frequent answer, ahead of 5. d4 and 5. Nc3. All of these protect or support the d5-pawn. The named Main Line is the counterattack 5. Bb5+ c6 6. dxc6 bxc6 7. Bc4 Nd5, also called the Botvinnik Variation. Black's knight takes a central post and the queenside pawn structure is loosened. Engines rate the starting position as roughly balanced, and Black scores slightly better than White in the database.