Opening Leak Lab

Four Knights Game: Spanish Variation

C48 1. e4 e5 2. Nf3 Nc6 3. Nc3 Nf6 4. Bb5

Black scores 44.8% here across 471 club games — but the 15.1% who answer a6 score 33.1%, 12 points worse.

What Black actually plays here

Across 471 games from a Lichess-derived book of club play, Black scores 44.8% in this position. These are the replies people choose, and how each one works out.

ReplyGamesShare Black scoresVerdict
d6 168 35.7% 52.4% holds up
Bc5 93 19.7% 44.6% holds up
a6 71 15.1% 33.1% below the line
Bb4 70 14.9% 36.4% below the line
Nd4 27 5.7% 59.3% holds up

"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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