Classical Variation, Modern Defense

The Modern Defense arises when Black meets 6. c4 by capturing on c4 rather than supporting d5 with 6...c6. Black gives up the d5 point, leaving White with the only central pawn, on d4, and holds an extra pawn for the moment. With c7 and c4, Black's pawns are doubled on the c-file, and the advanced c4-pawn is difficult to keep. The c- and d-files are half-open, and the fight centers on how quickly White regains the pawn and how much activity each side has at that point. The engine rates the position as roughly balanced.

White has three main ways to go after c4. 7. Nc3 is the most frequent; it develops the knight and leaves the recapture for later. 7. Na3, the engine's preference, sends the knight toward c4 and has given White the best results in practice. 7. Ne5 hits c4 at once and opens the long diagonal for the g2-bishop, but it has scored better for Black than the other two moves. The engine also considers the queen moves Qc2 and Qa4, which attack c4 directly.