1. d2d4  1... g8f6  2. c2c4  2... g7g6  3. g1f3  3... f8g7  4. e2e3  4... e8g8  5. f1e2  5... d7d6  6. b1c3  6... b8d7  7. e1g1  7... e7e5  8. b2b3 A somewhat slow move. Since the center will  be closed soon and both sides will have clear plans of playing on separate flanks, it made sense for White to push this pawn on b4 at once. 8... f8e8  9. h2h3 Another questionable decision. This pawn can well become a weakness very soon. Why should one voluntarily advance pawns on the side where one is weaker? 9... e5e4 The center is closed. Next Black will play on the kingside. His play is very typical and simple: push the h-pawn as far as possible and  transfer the knight from d7 to g5 in a clear attempt to checkmate the  enemy king. White on his turn will try to shatter the enemy queenside as  quick as possible, thus keeping the opponent busy. Ideally, he wants to  defend the opposite wing with as few pieces as possible. 10. f3d2  10... h7h5  11. b3b4 It is evident that Mamedyarov lost a tempo on the  queenside. 11... d7f8  12. f1e1  12... c8f5  13. c1b2  13... d8d7 The threat of a bishop sacrifice is  already in the air. 14. c3d5 Although White played carelessly up to  now, it is only this move that can be named a mistake. 14... f6d5  15. c4d5  15... d7e7 Now Black manages to regroup nicely. The  queen goes on a striking position at g5, whereas as Nepomniachtchi  explained the rook can defend the c7-pawn sideways, from e7. Thus the  queenside is stable and Black can concentrate on his kingside play. 16. a1c1  16... f8h7  17. d1c2  17... e7g5  18. c2c7 Mamedyarov ventures into complications, but  they favor his opponent instead as he is the one attacking the king. 18... f5h3  19. e2f1  19... g7f8  20. c7b7  20... h7f6 The pawn that Black sacrificed is a negligible price for the kingside attack he gained.