But this is a mistake! It looks like Grischuk could not  remember some important details.
1. b2b3 Despite the poor start, Carlsen does not mind experimenting. 1... e7e5  2. c1b2  2... b8c6  3. c2c4 Switching to the reversed Sicilian. 3... g8f6  4. g1f3  4... e5e4  5. f3d4  5... f8c5  6. d4f5 This position is super-fresh,  although there is one recent top-GM game. 6... d7d5 Grischuk  played this novelty relatively fast. Apparently, the Russian GM had  studied this line earlier at home. 7. f5g7 Carlsen accepts the pawn without much hesitation. 7... e8f8  8. c4d5  8... c5d4 The point behind Black's play. He wants to trap the opponent's  knight. 9. b1c3 The best chance.