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.