The last moves were natural, and the game turned into a queen endgame, the most difficult in chess (in my opinion). Here, for instance, just one move saves Black, and finding it with seconds on the clock is difficult.
1. g1f3  1... g8f6  2. c2c4  2... b7b6  3. b1c3  3... c8b7  4. d2d4  4... e7e6  5. a2a3 [%c_arrow f8b4;keyPressed;none;from;f8;opacity;0.8;to;b4;persistent;false,d4d5;keyPressed;ctrl;from;d4;opacity;0.8;to;d5;persistent;false] This is the so-called Petrosian Variation of the Queen's Indian Defense. The idea behind ​​White's fifth move is to avoid the pin with ...Bb4, now creating the positional threat of playing d4-d5, gaining space in the center. This line was a favorite of the young Garry Kasparov, and I remember studying as a teenager some beautiful wins in his fabulous book \"The Test of Time.\" 5... f6e4 [%c_effect e4;square;e4;type;Interesting;persistent;true] A rarer option than the pawn advance to d5, but also perfectly playable. This was the move played by Ulf Andersson in the game against Kasparov, one of the 13th world champion's most famous victories. 6. c3e4  6... b7e4  7. e2e3  7... f8e7  8. f1d3 The most played move with the idea of ​​exchanging bishops and then occupying the center with the pawn. 8... e4d3  9. d1d3  9... e8g8  10. e1g1  10... d7d6  11. b2b4  11... b8d7  12. f1d1  12... a7a5  13. c1b2  13... a5b4  14. a3b4  14... d8b8 [%c_arrow b8b7;keyPressed;none;from;b8;opacity;0.8;to;b7;persistent;false,a8a1;keyPressed;none;from;a8;opacity;0.8;to;a1;persistent;false,f8a8;keyPressed;none;from;f8;opacity;0.8;to;a8;persistent;false] Caruana's idea is to play Qb7, exchange rooks, and play Ra8. 15. d3e4 [%c_arrow e4c6;keyPressed;none;from;e4;opacity;0.8;to;c6;persistent;false] A tempting move with the idea of placing the queen on c6, but Black can equalize the game. 15... d6d5  16. c4d5  16... d7f6  17. e4c2  17... e6d5 If I were playing this game, I must admit that I'd have trouble knowing whether it's better to take with the pawn or with the knight, but Caruana's choice is probably the best: this way, he doesn't have to worry about the white center advancing. 18. f3e5  18... e7d6  19. b4b5  19... b8e8  20. a1a8  20... e8a8  21. d1a1  21... a8e8  22. c2c6  22... e8e7  23. a1a7 [%c_highlight b2;keyPressed;alt;opacity;0.8;square;b2;persistent;false,d6;keyPressed;alt;opacity;0.8;square;d6;persistent;false,c7;keyPressed;none;opacity;0.8;square;c7;persistent;false] White has a comfortable position since he has more space, but the problem is that, for now, there's nothing to attack. The same position without the dark-squared bishops, for example, would be difficult for Black, but as it stands, the bishop defends the c7-pawn and the knight defends the d5-pawn. 23... h7h5  24. h2h3  24... f8d8  25. c6c1 [%c_effect c1;square;c1;type;GreatFind;persistent;true][%c_arrow b2a3;keyPressed;none;from;b2;opacity;0.8;to;a3;persistent;false] With the idea of ​​playing Ba3 to exchange the bishops. 25... e7e6  26. e5c6  26... d8e8  27. b2a3 [%c_effect a3;square;a3;type;GreatFind;persistent;true] 27... f6e4  28. a3d6  28... e6d6  29. c6e5  29... e8c8 Here, White can claim a small advantage, but Carlsen's next move is a mistake. 30. f2f3 [%c_effect f3;square;f3;type;Mistake;persistent;true][%c_highlight e3;keyPressed;none;opacity;0.8;square;e3;persistent;false] Weakening the pawn on e3. 30... e4g3  31. c1a1  31... f7f6  32. e5d3  32... h5h4  33. g1f2  33... g8h7  34. a1b1  34... c8e8 [%c_arrow b1h7;keyPressed;none;from;b1;opacity;0.8;to;h7;persistent;false] A courageous move to be played with little time on the clock, not fearing a discovered check. 35. b1c2  35... e8e7 [%c_effect e7;square;e7;type;Inaccuracy;persistent;true] 36. d3e5  36... g3e4 [%c_effect e4;square;e4;type;GreatFind;persistent;true] The only move, but good enough. Black now has a draw, but against Carlsen, nothing is easy. 37. f3e4  37... f6e5  38. e4d5  38... e5e4  39. f2g1  39... d6d5  40. a7c7  40... e7c7  41. c2c7  41... d5b5 