Carlsen fights fiercely for his life. This is the only way  to demonstrate some activity and to bring the pieces into the game.
1. d2d4  1... g8f6  2. g1f3  2... e7e6  3. c1f4  3... b7b6  4. e2e3  4... c8b7  5. f1d3  5... f8e7  6. h2h3 In a must-win  situation, Aronian chooses to keep as many pieces on the board as he can. 6... c7c5  7. c2c3  7... c5d4  8. e3d4  8... e8g8  9. e1g1  9... d7d6  10. f1e1  10... b8d7  11. a2a4 White's plan is to gain as  much space on the queenside and ideally provoke weaknesses there. 11... a7a6  12. f4g3 A novelty. 12... f8e8  13. b1a3  13... e7f8  14. a3c4  14... d8c7  15. f3d2  15... b6b5 This move will likely be played sooner or later. 16. c4a3 Putting more pressure on Black. 16... b5a4  17. d1a4  17... b7c6  18. a4c2  18... c7b7 Carlsen played this obvious move  very quickly, but it is a blunder. 19. a3c4 Blitzed instantly. After this the world champion started  shaking his head in disbelief... 19... b7c7 ...and accepted the loss of two important tempi as calmly as he could under the circumstances. 20. c4a5  20... a8a7  21. a5c6 capturing the excellent bishop at once. 21... c7c6  22. b2b4  22... e8c8  23. c3c4 