1. d2d4  1... d7d5  2. c2c4  2... e7e6  3. b1c3  3... a7a6  4. c4d5  4... e6d5  5. g1f3  5... g8f6  6. c1g5  6... c8e6  7. e2e3  7... b8d7  8. h2h3  8... f8d6  9. f1d3  9... c7c6  10. g5f4  10... d8c7  11. f4d6  11... c7d6  12. e1g1  12... e8g8 This position has been played many times. Black is very solid, and the pawn on a6, which might have seemed like a waste of time when it was played on the third move, ends up being useful against the typical minority attack with b4-a4-b5. 13. a2a4 [%c_effect a4;square;a4;type;Interesting;persistent;true] I'm not sure if this is an idea straight from Caruana's famous analytical lab or if it was an over-the-board inspiration; the first option seems more likely. This move has been played just once before and is a positionally difficult choice, as Black can fix the pawn structure with a6-a5, which apparently favors him, as the dark-squared bishops have been exchanged. 13... a6a5 The natural reply, fixing the queenside before White plays a4-a5. 14. d1b3  14... g7g6 A new move. It's debatable whether this is the best way to create air for the king and not with h7-h6. Black will have some problems with this structure in the game, but putting the blame on this move seems a little unfair. 15. f3g5 [%c_effect g5;square;g5;type;Interesting;persistent;true] The knight on g5 will prove to be a very uncomfortable piece for Black. This is a curious change of direction, as White seemed more interested in the queenside. 15... f8e8  16. a1e1  16... d7f8  17. b3c2  17... f6h5  18. f2f4  18... f7f6 A good reaction, but Black has to find some extraordinary resources to maintain the balance. 19. g5e6  19... e8e6 [%c_effect e6;square;e6;type;Mistake;persistent;true] Black's position becomes very difficult to play now, and Caruana gives a masterclass on how to convert the advantage. The correct move is to capture with the knight. 20. f4f5 [%c_effect f5;square;f5;type;GreatFind;persistent;true] 20... g6f5  21. f1f5  21... h5g7  22. f5f3 White has a big positional advantage thanks to his better structure on the kingside. 22... a8e8  23. c2f2  23... f8g6  24. g2g4 [%c_effect g4;square;g4;type;GreatFind;persistent;true] Caruana begins the plan to advance the pawns on the kingside. Black's knights don't have a strong point, and the king is in danger.