1. c2c4  1... g8f6  2. b1c3  2... e7e5  3. g1f3  3... b8c6  4. g2g3  4... f8b4  5. f1g2  5... e8g8  6. c3d5  6... e5e4 This is considered the best reply according to theory, although other moves are possible. 7. f3h4  7... d7d6  8. e1g1  8... g7g5 Black bravely goes after the knight. There is a price to pay: the king is weakened. 9. d2d4  9... h7h6 This position has already been played in more than 80 games, and now comes something new from Caruana's opening lab that borders on the unbelievable. 10. g3g4 What can I say about this play $2 It seems absurd, but it's a fantastic and interesting idea, at the very least useful for a rapid game. The white knight is lost against other moves as well, but White usually try more conventional lines in the search for compensation. 10... f8e8 Keymer immediately makes a mistake, and his position becomes losing. We could say that Caruana's new move is a \"semi-bluff,\" because Black is doing well with accurate play, but not well enough to have a winning position. The bet is: will my opponent find all the best moves even with little time $2 And if that happens, Black's advantage is small, nothing too dramatic. On the other hand, there is the risk that Black will make a mistake and be immediately lost, as happened in the game. Finding this type of move in the analysis and having the courage to use it show the dual quality of Caruana's opening preparation. 11. h4f5 The white knight escapes, and the weaknesses around the black king make the position practically indefensible. 11... f6g4  12. f2f3  12... e4f3  13. e2f3  13... g4h2 A clever idea, but it doesn't change the evaluation. 14. f5h6  14... g8g7  15. g1h2  15... e8h8  16. a2a3  16... b4a5  17. b2b4  17... h8h6  18. h2g1 How ironic that it's Black who ends up with a piece trapped in the corner of the board after everything the white knight has been through. 18... c8h3  19. a1a2 A lovely rook shift through the second rank. 19... a5b6  20. c4c5  20... h3e6  21. f3f4 Protecting the knight and opening the kingside at the same time. 21... g5f4  22. c5b6  22... d8h4  23. f1f4 A rapid game is always subject to a mistake in its final minutes. Here it happens again, proving that not even Caruana is immune.