A novelty, as early as move seven! Caruana created a whole new system to  fight Carlsen's beloved Anti-Rossolimo line and was hugely successful in  the match so far.
1. e2e4  1... c7c5  2. g1f3  2... b8c6  3. f1b5  3... e7e6  4. b5c6  4... b7c6  5. d2d3  5... d8c7  6. e1g1  6... g8e7 