Modern Variation

The Modern Variation arises when White answers 3...Nf6 with 4. Bg5, pinning the knight against the black queen. The bishop is developed actively before e3 can shut it inside the pawn chain. The pin also bears on d5, since the f6-knight is one of that pawn's main defenders. Classified under ECO D50, this was the main line of the Queen's Gambit Declined for most of the twentieth century and is the starting point for the Orthodox Defense, the Tartakower and Lasker systems and the Cambridge Springs.

By far the most common reply is 4...Be7, chosen in roughly three games out of five. It breaks the pin and keeps the classical d5/e6 structure. After 5. e3 O-O 6. Nf3 the game reaches the Normal Line. The same position often comes from 1. d4 Nf6 2. c4 e6 3. Nf3 d5 4. Nc3 Be7 5. Bg5 O-O 6. e3, a move order that avoids the Nimzo-Indian. Continuing 6...Nbd7 gives the Orthodox Defense, where 7. Rc1 c6 8. Bd3 dxc4 9. Bxc4 shows the typical tempo struggle over when White commits the f1-bishop. The Heral Variation, 4...Be7 5. Bxf6, abandons the pin at once and hands Black the bishop pair to settle the structure early.

The second most popular reply is 4...Bb4, which answers the pin with a counter-pin on the c3-knight in the spirit of the Nimzo-Indian. White scores slightly above average against it. 4...c6 keeps Slav-type structures in reserve. 4...Nbd7, the Knight Defense, delays the decision about the f8-bishop, and Black's results with it are relatively good. 4...c5, the Been-Koomen Variation, strikes at the center immediately. The engine also ranks 4...dxc4 among Black's best moves, although it is not one of the common practical choices.

Play is mostly positional and heavily theoretical. It centers on the c8-bishop, the timing of ...dxc4 and ...c5, and White's use of the pin. The engine assesses the position as roughly balanced. In online play White wins slightly more often than Black, and draws are uncommon.