Open Defense

The Open Defense name is attached to the Catalan position after 1. d4 Nf6 2. c4 e6 3. g3 d5 4. Bg2 (ECO E01), where Black must settle the fate of the c4-pawn. The most common reply is the Closed 4...Be7, which also gives Black the best results. Next come 4...c6, reinforcing d5 and blunting the g2 bishop in advance, and 4...dxc4, the capture that gives the line its name. The check 4...Bb4+ aims to provoke an awkward block. The engine rates the position as roughly balanced.

After 4...dxc4, White can recover the pawn at once with 5. Qa4+ Nbd7 6. Qxc4. In the Alekhine Variation, 6...a6 7. Qc2 follows. The more usual 5. Nf3 lets the pawn wait while the long diagonal opens. Black then chooses between the Classical Line 5...Be7, in which the pawn is usually returned for smooth development, and attempts to hold it, such as 5...a6 with ...b5 in view. The Modern Sharp Variation, 5...Nc6 6. Qa4 Bb4+, produces more forcing play. In these lines Black accepts an unbalanced center and queenside weaknesses, and White's compensation rests on the g2 bishop and a lead in development.