comment: Since it was used in some games of the Carlsen-Caruana match, this move has become as important to opening theory as the old main line with 7.Bg5.
context: 1. e2e4  1... c7c5  2. g1f3  2... b8c6  3. d2d4  3... c5d4  4. f3d4  4... g8f6  5. b1c3  5... e7e5  6. d4b5  6... d7d6 