context: 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  7. d1a4  7... c7c6 The pawn on g2 is still impossible to protect, but Caruana has an idea. 8. e2e4 The position looks good for White now. If Black takes on g2, then the knight goes to f5 and later to d6. But Keymer finds a wonderful move. 8... g7g5 Black suddenly explodes the position with exotic pawn tension in the center and on the flank. The pawn chain is impossible to sustain, and Black emerges from the complications with an excellent position. 9. g3f5 The best decision. 9... h4f5  10. e4f5  10... c8f5  11. a4c2 