How to Play the Zukertort Opening: Reversed Mexican Defense: d4 as White

The engine's best move in this position is c5, continuing with g3, Nc6, and Bg2. That pawn push seizes space in the centre and eyes your knight on b5. Across 35,106 games where Black chose c5, White scored only 43.9% — the lowest winning percentage of any major reply. That makes ...c5 the scariest test of your opening. If Black plays c5, you're in a tough fight. But here's the good news: many club players don't know that ...c5 is the critical move.

Your practical chances jump when Black picks one of the inaccurate replies. The statistics are clear: a6, c6, and e5 are all labelled inaccuracies, each losing roughly 0.7–0.8 pawns compared to the engine's recommended c5. With a6 or c6, Black loses about 0.8 pawns of advantage; with e5, about 0.7. Here is how the game results shift in your favour: - e5 (3,482 games): White scores a commanding 60.9%. A dream reply. Black's centre looks active, but your knight on b5 remains annoying and Black's pawn structure can become a target. - a6 (5,391 games): White scores 49.5% — close to even, a huge improvement from the 43.9% you get after c5. The threat of Nb5–a3–c4 gives you a nice outpost. - c6 (4,363 games): White scores 49.7%, again very playable. The knight can retreat to a3 or d4, and Black's ...c6 sometimes wastes a tempo. Spot these three moves in the drill, and you will already be outperforming the average result from the main line.

Since c5 is the engine's best move and the most common (35,106 games), you need a plan for when Black plays it. The engine's continuation is: c5 g3 Nc6 Bg2. That set-up — fianchetto on g2 and a quick g3 — is your go-to recipe. Develop naturally: - g3 gives your light-squared bishop a strong diagonal, fighting for control of the centre and targeting Black's d4 pawn. - Bg2 completes the fianchetto and prepares to castle quickly. - Your knight on b5 can be harassed, but don't rush it. Sometimes it stays there for a while, putting pressure on c7 and a7. Remember: the position is slightly worse for you, so play solidly and look for equalising trades. Don't overextend. The drill will let you practise this exact development scheme against Black's c5.

The overall database results across 77,399 games paint a sobering picture: White wins 46.3%, Black wins 50.0%, and draws are rare at 3.7%. That five-percent gap reflects the engine's -0.50 evaluation. But look at how much those win rates vary by Black's choice: - After c5: White just 43.9% — tough. - After e5: White 60.9% — a dream scenario. - After a6 or c6: roughly 49.5% — close to equal. The lesson is simple: your success in this opening depends heavily on whether Black knows the best move. If they play anything else, your odds improve dramatically. The drill will train you to exploit those inaccuracies while keeping your head above water after ...c5.