1. d2d4  1... g8f6  2. c2c4  2... e7e6  3. g2g3  3... d7d5  4. f1g2 The Catalan opening is one of the most important in chess. Nowadays, every professional chess player must be familiar with its theory. 4... d5c4 One of the best options for Black, along with developing the bishop on e7 or b4. 5. g1f3  5... b8c6  6. d1a4 Trying to win back the pawn, before Black can play Rb8-b5, which leads to sharper play. 6... f8b4 