Advance Variation, Main Line

The Main Line of the Advance French arises when White meets 5...Qb6 with 6. a3, the most important line of the variation in current practice. The quiet pawn move takes the b4-square away from Black's pieces, ruling out incursions there, and prepares b2-b4 to claim space on the queenside. Once the b-pawn has advanced, the queen on b6 no longer has a target on b2, so the c1-bishop is released from guarding it and can join the defense of the center.

In online games Black most often exchanges with 6...cxd4, with 6...Bd7 close behind. The bishop move is a quieter, flexible choice that postpones the g8-knight's development, since the bishop belongs on d7 in almost every Advance structure anyway. Theory treats 6...c4 as the principal answer: it relieves the central tension and stops b4 by threatening to capture en passant, producing a closed fight over b3. The Lputian Variation, 6...Nh6, routes the knight toward f5 without blocking the f8-bishop's path to c5; capturing with 7. Bxh6 is regarded as unwise. The engine rates the position as roughly level, and White scores somewhat better than Black online.