Carlsen rejects the offer.
1. e2e4  1... c7c5  2. g1f3  2... b8c6  3. f1b5  3... e7e6  4. e1g1  4... g8e7  5. f1e1  5... c6d4  6. f3d4  6... c5d4  7. c2c3  7... a7a6  8. b5f1  8... e7c6  9. b2b4 Fighting for the center from the flank. 9... f8e7  10. a2a4  10... e8g8  11. b1a3  11... d4c3 Carlsen trades the central pawn, but  does so at a moment when the opponent somewhat spoiled his coordination.  Plus, he gains a long diagonal for his bishop. 12. d2c3  12... e7f6 In a  must-win situation Vachier-Lagrave uncorks a novelty. 13. b4b5 New and interesting.