Zukertort Opening: Old Indian Attack
A06 1. Nf3 d5 2. d3
Black scores 45.7% here across 410 club games — but the 16.8% who answer c5 score 40.6%, 5 points worse.
What Black actually plays here
Across 410 games from a Lichess-derived book of club play, Black scores 45.7% in this position. These are the replies people choose, and how each one works out.
| Reply | Games | Share | Black scores | Verdict |
|---|---|---|---|---|
| Nc6 | 110 | 26.8% | 47.3% | holds up |
| Nf6 | 100 | 24.4% | 50.0% | holds up |
| c5 | 69 | 16.8% | 40.6% | below the line |
| e6 | 32 | 7.8% | 40.6% | below the line |
| Bg4 | 26 | 6.3% | 40.4% | 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.