1. c2c4  1... g8f6  2. b1c3  2... e7e5  3. g1f3  3... b8c6  4. g2g3  4... d7d5  5. c4d5  5... f6d5  6. f1g2  6... f8c5 This variation has become popular since Caruana used it in his 2018 match against Carlsen. Of course there is nothing wrong with the main line, 6...Nb6. 7. e1g1  7... e8g8  8. d1c2 A new try. This move was played by Carlsen in a rapid game this year. 8... c6d4 The game quickly goes down little-trodden paths. 9. c2e4 The first new move. 9... d5c3 