Sicilian Defense: Old Sicilian: what to play after Nc6?

In the Sicilian Defense: Old Sicilian (ECO B30), White primarily chooses between the Rossolimo Attack with Bb5 or the Open Sicilian transition via d4. While d4 is the most frequent continuation, played in 45.9% of the 129 million recorded games, the engine evaluation slightly favors Bb5 at +0.27 due to its immediate pressure on the c6 and its avoidance of the heavy theoretical lines found in the Open Sicilian.

The Rossolimo Attack with Bb5

The move Bb5 is the second most popular choice, appearing in 12.7% of games. This approach aims to disrupt Black's pawn structure or force a concession in development, scoring a 52.2% win rate for White. The main line often continues Bb5 g6 O-O Bg7 Re1 e5, where White focuses on rapid mobilization and control of the center without immediately opening the d4 square.

Transitioning to the Open Sicilian

The most common response is d4, occurring in 77 million recorded games. This move leads to an engine evaluation of +0.32 and typically results in the sequence d4 cxd4 Nxd4 Nf6 Nc3 e5. By playing d4, White accepts a more tactical and theoretical battle, aiming to utilize the central space and active piece play characteristic of the Open Sicilian structures.

Alternative Development Options

White may also opt for slower developmental moves such as c3 or Nc3. The Alapin-style c3 is played in 9.8% of games and carries a strong 52.1% score, often leading to c3 Nf6 e5 Nd5 d4 cxd4. Meanwhile, Nc3 is seen in 7.9% of games, frequently transposing into Closed Sicilian or King's English structures after Nc3 e5 Bc4 d6 d3 Be7. The quiet Be2 remains a rare sideline, played in only 0.7% of games with an engine evaluation of +0.07.