Opening Leak Lab

Sicilian Defense: Kan Variation, Knight Variation

B43 1. e4 c5 2. Nf3 e6 3. d4 cxd4 4. Nxd4 a6 5. Nc3

Black scores 52.0% here across 447 club games — but the 21.0% who answer b5 score 48.9%, 3 points worse.

What Black actually plays here

Across 447 games from a Lichess-derived book of club play, Black scores 52.0% in this position. These are the replies people choose, and how each one works out.

ReplyGamesShare Black scoresVerdict
Qc7 216 48.3% 55.8% holds up
b5 94 21.0% 48.9% below the line
Nc6 69 15.4% 44.2% below the line

"Below the line" means the reply scores at least three points worse than the position does overall. Replies played fewer than 25 times are left out: the sample is too small to read.

Is this costing you anything?

A table of averages cannot tell you whether you go wrong here — only your own games can. Opening Leak Lab reads your Chess.com or Lichess archive, finds the decisions you repeat, and checks each one against this book and a bundled Stockfish.

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