1. e2e4  1... e7e5  2. g1f3  2... b8c6  3. f1b5  3... a7a6  4. b5a4  4... g8f6  5. e1g1  5... f6e4  6. d2d4  6... b7b5  7. a4b3  7... d7d5  8. d4e5  8... c8e6  9. c2c3  9... f8c5 Nothing up to here can be considered a huge surprise. Hikaru has only been playing e4 with White, and Caruana repeated the same Bc5 Open Spanish that he recently chose against MVL. 10. b1d2  10... e8g8  11. b3c2  11... e4f2  12. f1f2  12... c5f2  13. g1f2  13... f7f6  14. d2f1  14... f6e5  15. f2g1 All of this is well known theory, but I think Caruana fell into the same practical trap that Firouzja did against Nepo. I'm quite confident Black's position is objectively fine here, but in practice, it feels so much easier to play the White side. 15... d8d6  16. c1e3  16... e6f5  17. c2b3  17... a8d8  18. d1e1  18... c6a5  19. e1f2  19... a5b7 Both sides were still playing very fast. 20. a1e1  20... c7c5  21. f1g3  21... f5d3  22. f2d2  22... c5c4 In my opinion, this is the move that lost Caruana the game. The position is incredibly hard to understand, but I think the main point is that Black will not be able to maintain his pawn on e5. It will inevitably have to move to e4. When this happens, Black will really regret having pushed c5-c4 because he loses any hope of fighting for the dark squares, plus the light squared bishop can end up stuck on d3 and unable to fight on other relevant parts of the board. White is only a bit better still, but Black's position feels nearly impossible to play. 23. b3d1 White does not exchange the bishops. He has already seen that d3 will become a piece of dead wood. 23... d8d7  24. e3f2  24... d7f7  25. g3h1 An excellent decision from Hikaru. The move is not at all subtle, White wants to take on e5, or to play Bg3 next. Black clearly will have to move the e-pawn. 25... e5e4  26. f3d4 This is exactly the kind of position that I think is a practical nightmare for Black. Long term, he will face huge issues as his pawns are blockaded in the center, and White will eventually take them by having a larger total number of pieces on the board. Black's compensation is that one of his pieces is bigger than White's, but the main power of a larger piece over a smaller piece, such as a rook over a bishop, is being able to attack multiple targets at once. And what do we have here $2 Black's rooks are both clearly on their best squares already. In fact, all of his pieces look nice and active. But what is there to target $2 White has no weaknesses. Slowly but surely, he will activate his pieces and organize them to attack the pawns. Caruana surely could have defended better from here, but in human terms, I think the game is already more or less lost, even though the machine gives White only a 0.5 advantage or so. I think his big mistake was c4.