Zukertort Opening: Old Indian Attack: Bf5 — A Small Edge for White

The move 3.c4 directly challenges Black's pawn on d5. If Black captures with dxc4, you recapture with dxc4 and open the centre on your terms — the engine's preferred continuation goes 3.c4 dxc4 4.e4 Bg4 5.d4. That gives you a strong pawn duo in the centre and a space advantage. If Black doesn't capture, you can push cxd5 later, leaving White with a semi-open c-file and a slight lead in development. Your bishop on f1 has clear prospects, and your knight on f3 is well placed. The key idea is simple: don't let Black keep that d5 pawn unchallenged.

Stockfish's top choice for Black is 3...dxc4, played in 732 games. After 4.e4 Black's bishop must move, and the engine suggests 4...Bg4. Then 5.d4 leaves you with a classic centre: pawns on e4 and d4, a knight on f3, and options to develop quickly with Be3 and Nc3 (or c3 if you prefer). White's score after 3...dxc4 is only 47.8%, but that's partly because it's Black's best try — the engine still says +0.34 is in your favour. Trust the evaluation: you have a slight pull in a position that is easy to play for a club player, while Black has to be accurate.

Black's most popular reply is 3...e6, with 778 games. White scores 49.2% here — solid, but Black equalises more easily than after other moves. The real opportunities come against Black's less accurate tries: - 3...c6 (211 games): White scores 55.9%. This is a big number. Black's pawn on c6 doesn't help contest the centre, and the engine calls it an inaccuracy (loses ~0.5 pawns). - 3...Nf6 (236 games): White scores 52.1%. Despite being the third most common reply, the engine flags it as an inaccuracy (loses ~0.6 pawns). - 3...Nc6 (107 games): White scores 51.4%, but this is actually a mistake that loses ~2.5 pawns. The best move was 3...d4, but that's rarely played (139 games) and gives Black a poor 42.4% score — so you're doing well if Black pushes the d-pawn. In short, if Black doesn't play 3...dxc4 or 3...e6, you're already getting the upper hand.

If Black plays 3...Nc6, you have a big advantage to press. The engine says Black should have played d4 instead — that move loses ~2.5 pawns. Your plan? Continue developing naturally, aiming to open the centre. After 3...Nf6 or 3...c6, the advantage is smaller but still real. Against 3...c6, for instance, you have a 55.9% winning chance. In all these cases, the engine wants you to stay consistent: capture on d5 when it helps you, build your centre, and don't rush. The +0.34 edge is yours to keep as long as you play principled chess.