Mamedyarov takes his time to improve the position. This move avoids Bg4 and thus prepares Rad1.
1. d2d4  1... d7d5  2. g1f3  2... g8f6  3. c1f4  3... c7c5  4. e2e3  4... e7e6  5. b1d2  5... d8b6  6. c2c4 [%c_effect c4;square;c4;type;Interesting;persistent;true] Mamedyarov, of course, plays the London System in an enterprising way. This dynamic move is rare, but has been played a few times by Erigaisi recently. 6... b8c6 [%c_effect c6;square;c6;type;GreatFind;persistent;true] The best reply. Accepting the pawn is too risky. 7. f1d3 Played after a long think. This is an important position for opening theory. 7... c5d4  8. e3d4 The real novelty. 8... c6d4  9. e1g1  9... f8e7  10. c4d5  10... d4f3  11. d1f3  11... e6d5 A solid move, taking the squares from White's knight and opening the diagonal for the bishop. 12. f1e1  12... c8e6  13. d2b3  13... e8g8  14. f4e3  14... b6d6  15. e3f4  15... d6b6  16. f4e3  16... b6d6  17. e3c5 Mamedyarov decides to keep the game going, instead of accepting a draw by repetition. It's a bold decision that will pay dividends, since he will achieve a winning position later in the game. 17... d6d8  18. c5d4  18... b7b6 A rather ugly move, but it's not very easy for Black to find a plan. Now he can try something like Rc8-Bc5 or Qd7-b7 in some positions.