1. d2d4  1... f7f5 A good version of the \"Dutch Defense.\" Black opens the diagonal for the bishop and, for the moment, stops e2-e4. The alternatives are worse, although they were played in the other games. 2. h1g3  2... d7d5 Preventing e2-e4. The weakness of the e5-square is not felt since Black wants to place a pawn there soon. 3. f2f3  3... e7e5  4. d4e5  4... h8g6 A creative move that tries to exploit the weakness of the g2-pawn. 5. f3f4  5... g6h4 This is Black's idea: The pawn on g2 cannot be protected. Now White should make room for the rook on e1, but Caruana takes a drastic decision. 6. c2c4  6... d5c4 