1. c2c4 The most natural move. 1... g8f6 The knight is vulnerable on f6, as we will see in the game. In addition to the potential capture with the bishop on a1, another problem is that White can advance e4-e5, attacking it. 2. g1f3  2... b7b6  3. b2b4  3... c7c5 Caruana isn't afraid of losing the h-pawn. 4. a1e5 A very subtle and interesting move. Keymer wants to close the diagonal before capturing on f6. 4... d7d6  5. e5f6  5... e7f6  6. b1h7  6... h8g6 The game becomes sharp. Black has problems with the king, as it has no safe place to go to. But Black has good control of the center, and White also needs some time to castle on the kingside. 7. e2e3 Accelerating development. 7... c5b4  8. f1e2 White intends to castle, and Black has a problem with the king. 8... c8c5 The wrong plan. 9. h1g3 An accurate reply. 9... b8c7 