Nimzo-Larsen Attack

The Nimzo-Larsen Attack (ECO code A01) is a chess opening that begins with 1. b3. A quiet opening where White fianchettoes the queenside bishop. Popularized by Bent Larsen and Aron Nimzowitsch. Leads to flexible positions where piece activity matters more than pawn structure.

The main line of the Nimzo-Larsen Attack is 1. b3. It is classified under ECO code A01 and falls in the Flank Opening family of chess openings. From this starting position, both sides have well-established plans — White typically continues with natural developing moves while Black follows the response patterns described above.

The Nimzo-Larsen Attack is more strategic than tactical, which can make it harder for beginners to feel like they're "doing something" — but the upside is fewer forced lines to memorize. If you understand the typical pawn structure and middlegame plans, you can play this opening from move 1 without needing 15 moves of theory. Pair it with engine review at chess.rodeo to see where your understanding breaks down.

The Nimzo-Larsen Attack is classified as ECO code A01. ECO (Encyclopaedia of Chess Openings) is the standard five-letter classification system developed by Chess Informant in the 1970s — A-codes cover flank openings, B-codes 1.e4 replies that aren't 1...e5, C-codes 1.e4 e5 openings, D-codes 1.d4 d5 systems, and E-codes Indian Defenses. You can browse all openings by ECO code in our free opening database.

Use chess.rodeo for full Stockfish analysis of your Nimzo-Larsen Attack games — no account required, no daily cap, no paywall. Paste your PGN and get instant engine evaluation on every move, including the opening phase. For move-by-move replay without engine output, use our free PGN viewer. Both are completely free with no signup.