Anderssen Counterattack

The Anderssen Counterattack departs from the usual 4...c6 or ...Nf6 development of the 3...Qa5 main line. Black instead plays 4...e5, challenging d4 immediately. The queen on a5 supports this break and pins the knight on c3. Black thereby avoids the quiet Caro-Kann-like setups in favor of open lines on the d- and e-files, but must accept that 5. dxe5 wins a pawn for the moment. The engine gives White a clear advantage, and White scores better than Black in online games.

The capture 5. dxe5 is the most common reply. After 5...Nc6 6. Nf3 Bb4 7. Bd2, the Orthodox Attack, Black develops quickly and pins the c3-knight, using pressure on e5 and the queen's activity to seek compensation. The Goteborg System, 5. Nf3, develops before resolving the central tension. Against it, 5...Bg4, the Collijn Variation, pins the knight and increases the pressure on d4. The quieter 5. Bd2 is played almost as often as 5. Nf3. It breaks the pin and frees the c3-knight to gain time against the queen.