Queen's Pawn Game: Accelerated London System: what to play after Bf4?

In the Queen's Pawn Game: Accelerated London System (ECO D00), the position after Bf4 presents Black with several robust defensive setups. The engine's top recommendation is the immediate counter-strike c5, which challenges the center and carries an evaluation of +0.08. While c5 is the most theoretically precise response, the most popular choice in the database is Nf6, played in 26.4% of over 88 million recorded games.

The Strategic Goal of c5

The move c5 is designed to pressure the d4 pawn before White can solidify the structure with e3. By attacking the center immediately, Black aims to create tension that often leads to the main line c5 e3 Nf6 Nf3 Nc6 Nbd2. This approach is statistically significant, appearing in 7.51 million games, and it prevents White from achieving the comfortable, uncontested development typical of the London System.

Solid Development with Nf6 and e6

For players preferring a more classical setup, Nf6 and e6 remain highly effective alternatives. Nf6 is the most frequent continuation, maintaining flexibility and preparing for kingside development. Similarly, e6 is chosen in 19.0% of games, often leading to a solid structure after e6 e3 c5 Nf3 Nf6 c3. These moves prioritize safety and piece coordination, resulting in evaluations of +0.10 and +0.16 respectively.

Contesting the Bishop with Bf5

Another common strategy involves developing the light-squared bishop to f5 to mirror White's f4. The move Bf5 is played in 13.0% of games and carries an engine evaluation of +0.11. This leads to a symmetrical struggle for control over the central dark squares, typically continuing with Bf5 c4 e6 Nc3 Nf6 Nf3. This line is effective for neutralizing White's early bishop activity and ensuring Black does not fall into a passive position.