Carlsen is immediately taking advantage of his opponent's sloppy play. He is heading to a favorable King's Indian Attack setup.
1. c2c4  1... g8f6  2. g1f3  2... e7e6  3. g2g3  3... d7d5  4. f1g2  4... f8e7  5. e1g1  5... e8g8  6. d2d3 Reti instead of the Catalan. 6... a7a5  7. b1c3  7... c7c6 Too passive.