But Caruana  is as cold-blooded as he can be.
1. d2d4  1... d7d5  2. c2c4  2... c7c6  3. g1f3  3... g8f6  4. e2e3  4... c8f5  5. b1c3  5... e7e6  6. f3h4  6... f5e4  7. f2f3  7... e4g6  8. c1d2  8... f8e7  9. h4g6  9... h7g6 Caruana chose a very solid line that he tested last  year at the (ongoing) Candidates. 10. d1c2  10... b8d7  11. e1c1 Donchenko castles under a pawn attack but hopes to open the  center and make it to the enemy king first. 11... a7a6 Here a7-a6 is aiming for a quick queenside action. 12. g2g4 A novelty, played after 10 minutes of thought. But since  Donchenko blitzed his next moves, it might have been only to refresh his  memory. 12... d5c4  13. f1c4  13... b7b5 Obvious, and somewhat provocative. 14. c4e2  White simply retreated. 14... c6c5  15. d4d5 The first real in-depth thought in the game (more  than half an hour). As it was mentioned before White should logically try  to get to the enemy king before the queenside explodes, and he is ready to part with a pawn for this aim. 15... f6d5 And almost the same amount of time spent by Black. 16. c3d5  16... e6d5  17. f3f4 The point behind the sacrifice. White is ready to  seize the light squares after Be2-f3! 17... b5b4 In order to secure the  a5-square for the queen. 18. e3e4 Another tough decision by the German GM. 18... d5d4 This pawn will play an important part in Caruana's  counterattack. 19. e4e5 With the idea of e5-e6! 19... d7b6 Out of the tempo. 20. e5e6 Donchenko is opening the black king.