Prophylaxis against Black's future plan (f7-f6 to  protect the pawn after which he can start disturbing the knight with  g7-g5-g4 ultimately winning the d2 pawn.)
1. e2e4  1... c7c5  2. g1f3  2... b8c6  3. c2c3 Dubov revealed after the game that he expected  the appearance of the Alapin, as he has "pretty horrible score against  it." 3... g8f6  4. e4e5  4... f6d5  5. f1c4  5... d5b6  6. c4b3  6... c5c4  7. b3c2  7... d7d5  8. e5d6  8... d8d6  9. e1g1  9... c8g4  10. d1e2  10... e8c8  11. b1a3  11... d6e6  12. e2e6  12... g4e6  13. b2b3  13... e6d5  14. b3c4  14... b6c4  15. a3c4  15... d5c4  16. f1e1 Both players are playing fast but it is again Dubov who  uncorks a novelty. 16... c4d3  17. c2d3  17... d8d3 It seems as Dubov had analyzed this and since another match is about to be played tomorrow, he did not want to share more details  about the position. 18. e1e3 After this, Nakamura will suffer. 18... d3d7  19. c1a3 "Black is slightly better." (Dubov) 19... e7e5  20. a3f8  20... h8f8 