Polish Opening: Czech Defense 3...Nf6 – How Black Should Respond

With 1.b4, White tries to claim space on the queenside and develop the bishop early. Your reply 1...e5 stakes a claim in the centre, and after 2.Bb2 d6 you reinforce it while keeping options open. The move 3.c4 by White supports b4 and prepares to expand, but it also loosens the d4 square. Your third move, 3...Nf6, develops with tempo — the knight eyes the e4 square and threatens to harass the bishop on b2 or prepare ...e4 at the right moment. The engine evaluates this position at +0.10, which is essentially a dead level game. You are neither better nor worse; think of it as a clean starting line. Your job is to develop naturally, keep the centre solid, and wait for White to overreach.

White's most common move, e3 (35,602 games), scores only 50.8% — barely above average. White intends to develop the kingside with Be2 and then g6, building a solid but passive setup. The engine's best continuation runs e3 g6 Be2 Bg7, and you can see the idea: Black fianchettoes the dark-squared bishop, completing harmonious development while White's b1-knight remains undeveloped. After Be2 Bg7 you have a flexible position — you can castle, then decide whether to strike in the centre with ...d5 or continue piece play. White's score of 50.8% from e3 tells you this line is nothing to worry about. Just develop with g6 and Bg7 and you'll have perfectly comfortable play.

Three of White's options are outright inaccuracies or mistakes, and recognising them gives you a chance to seize an edge. Nf3 is an inaccuracy costing about 0.7 pawns — White should have played e3 instead. This early knight development blocks the f-pawn and does nothing to challenge your centre. b5 is also an inaccuracy (losing ~0.6 pawns) that weakens the queenside pawn chain without good reason. d4 is the worst offender — a full mistake costing roughly 1.1 pawns. White pushes the d-pawn too aggressively, opening lines before development is complete. In all three cases, your solid setup with ...d6 and ...Nf6 means you can punish these overambitious moves with natural play: central breaks, developing moves, or exploiting the weakened squares. The drill will let you practise against each one.

The numbers from 78,084 real games paint a clear picture. White's best realistic options all score right around 50% — e3 (50.8%), Nc3 (50.6%), Nf3 (50.0%), and even the dubious b5 (50.0%). Only d4, the clearest mistake, drops White to 44.4%. This means that in the Czech Defense c4, Black is never under serious pressure from the opening. You are playing for a win just as much as White is. The 45.8% Black win rate (versus 50.1% White) is close to typical for any quiet opening, and the tiny 4.1% draw rate shows that this line leads to unbalanced, fighting chess — exactly what you want as Black.