Scandinavian Mainline: a3 — Playing for Equality as Black

After 1.e4 d5 2.exd5 Qxd5 3.Nc3 Qa5 4.a3 c5, White has a few extra tempi and the bishop pair still to come, but your position is solid. The key for Black is to complete development quickly, castle, and put pressure on White's centre. If White plays imprecisely — and the statistics show they often do — your equalising chances jump. In the Lichess database, Black scores 45.7% from this exact position, with another 3.9% drawn. That is a healthy counterpunching record for a line where the engine gives White a slight plus. Your queen is a little exposed on a5, but with the pawn on c5 you have already staked a claim in the centre. The next few moves are about giving that queen a safe haven while not falling behind in development.

Stockfish's top pick is 5.Nf3, followed by 5…Nf6 6.d4 a6. This is the line you should be ready for. White develops a piece, attacks nothing directly, and waits. After 6.d4 you need to meet the centre challenge — the database shows …a6 is the engine's continuation, preparing …Bf5 or …e6 without letting a white piece land on b5. If White deviates from Nf3, you are already in good shape. The three most‑played replies that the engine flags as inaccurate or worse are: - 5.d3 (4,093 games) – an inaccuracy costing about 0.5 pawns. White scores only 49.1%, meaning you actually score better than White from here. - 5.Bb5+ (1,605 games) – also an inaccuracy, losing about 0.6 pawns. White scores exactly 50.0%. - 5.Qf3 (465 games) – a full mistake, losing about 1.1 pawns. White scores 55.5% here, but that number is inflated by lower‑rated play. Against any of these, you can seize the initiative.

Let's look at what you can do when White does not play Nf3. - After 5.d3: White's setup is passive. You can develop naturally with …Nc6, …Bf5 or …Bg4, and …e6, aiming to castle quickly. The engine says White's edge has already slipped. Look for the moment to push …d5 or …e5 — White's d3 pawn blocks their own light‑square bishop, so you often get a pleasant game. - After 5.Bb5+: This check looks tempting but it wastes time. Simply block with …Bd7 (or …Nc6, though …Bd7 is cleaner). After …Bd7, if White trades on d7 you recapture with the queen, activating her. You will finish development ahead of White. - After 5.Qf3: White brings the queen out early, inviting …Nc6 with tempo (threatening …Nd4). After …Nc6, if White plays 6.Bb5 you have …Qb6, hitting b2 and forking the bishop. Your counterplay starts immediately.

The numbers tell a clear story: Nf3 is the only move that keeps White's advantage intact (51.6% White score). Every other popular continuation hands you better chances. - 5.d3: White scores 49.1% — that is below parity. Black outplays White in practice. - 5.Bb5+: White scores exactly 50.0%. A dead even result from a position where the engine expects White to be better. - 5.d4: White scores 53.8%, the highest of any common line, but this is also the most natural and double‑edged move. If you know your Scandinavian, you can meet 5.d4 with …cxd4 6.Qxd4 Nc6, when White's queen is again a target. The 53.8% includes a lot of White wins from tactical oversights — stay sharp and you will hold. - 5.Qf3: 55.5% for White sounds scary, but the engine calls it a mistake. The high White score likely comes from lower‑rated players mishandling the queen sortie. In the drill, you will learn the precise refutation.