Firouzja wants to keep his extra pawn.
1. d2d4  1... g8f6  2. c2c4  2... e7e6  3. g1f3  3... d7d5  4. b1c3  4... b8d7  5. c1g5  5... h7h6  6. g5h4  6... f8e7 The QGD  specialists Kramnik and Short often used this line, which means it cannot  be bad for Black. 7. c4d5  7... f6d5  8. h4e7  8... d8e7  9. e2e4 Now after the knight trade... 9... d5c3  10. b2c3  10... e8g8 ...the position is similar to the Neo-Tarrasch  Defense. It should be noted though that Carlsen has a lot of remarkable  wins in this pawn structure (although he typically gets it from the  Grunfeld Defense.) 11. f1d3  11... c7c5  12. e1g1  12... c5d4  13. c3d4  13... b7b6  14. a2a4 N A  logical novelty. White frees himself of the isolated pawn and creates a  weakness for the opponent instead. 14... c8b7  15. a4a5  15... b6a5  16. a1a5  16... d7f6  17. f1e1  17... f8d8  18. d1a1 The world  champion puts pressure on the queenside, but in reality he is waiting for  a good moment to strike in the center. 18... e7c7 A cool move by  Firouzja. The pawn is not in danger. 19. h2h3  19... a7a6  20. a5c5 Before doing anything concrete in the center, Carlsen  tries a couple of other ideas. 20... c7f4  21. c5e5 Intending to trap the queen with g2-g3. 21... f6d7  22. e5a5  22... d7f6 Not much progress here. Then it is time for the standard  break: 23. d4d5  23... e6d5  24. e4e5 The point behind the sacrifice. Diagonals  and files are opened for the white pieces, as well as a fabulous outpost  in the center. 24... f6e4 This diagonal should be locked. 25. a1d4  That is the difference with the similar line from above. Carlsen wants to  gain a few tempi chasing the enemy queen backwards. 25... d8c8 So far, Firouzja has defended well and now he threatens to swap a pair of rooks  with Rc8-c1. 26. a5a1  26... a6a5  27. a1b1 