Closed, Korchnoi Defense

The Korchnoi Defense is the logical follow-up to 2...e6 in the Closed Sicilian. Once White commits to the fianchetto with 3. g3, Black plays 3...d5 at once and contests e4 while the bishop is still on f1. This is the central break the closed setups normally try to hold back. Black gets a French-like pawn chain with c5, d5 and e6 rather than the slow ...g6 and ...d6 structure of the traditional Fianchetto Variation. White must settle the central tension before attacking on the kingside.

The most common reply is 4. Bg2, which keeps the fianchetto plan and lets Black decide whether to take on e4. The main alternative, 4. exd5, resolves the tension at once and opens the center. 4. d3 holds e4 with a pawn, and the engine also considers 4. Bb5+. The engine rates the position as roughly balanced. Lichess results are close to level, with a slight edge for White, and the line sees moderate use rather than heavy theoretical traffic.