1. d2d4  1... g8f6  2. g1f3  2... d7d5  3. c2c4  3... e7e6  4. g2g3 Carlsen keeps milking his amazing Catalan WCC preparation. 4... d5c4  5. f1g2  5... f8b4 Mamedyarov chooses a line that was tested by Topalov in both his WCC matches against Kramnik and Anand—and which was also often a choice of Carlsen himself. 6. c1d2  6... a7a5 