That is the price for the good knight: the only open file is in Aronian's hands and he infiltrates with his major pieces.
1. e2e4  1... c7c6  2. d2d4  2... d7d5  3. e4d5  3... c6d5  4. f1d3 The Exchange line that Fischer revived in the 1970s lives a new life thanks to the rise of the London System. A lot of positions transpose from both the openings and the pawn chains are quite similar. 4... g8f6  5. h2h3 Underlining Black's major problem in the position: the future of his light-squared bishop. 5... b8c6  6. g1f3  6... c6b4  7. b1c3 This is quite an interesting sideline, but should not have come as a major surprise. Aronian is playing his Ragozin with colors reversed. 7... g7g6 Still trying to solve the bishop problem. 8. f3e5  8... a7a6  9. e1g1  9... f8g7  10. f1e1  10... e8g8  11. c1g5 White's plan is very easy and straightforward: bring the queen out, trade the dark-squared bishop, and mate on the kingside. 11... b4d3 Lines like the above-mentioned forced Keymer to make up his mind. 12. c2d3 Played without any thought $1 Aronian is already envisioning perfect domination with the beautiful knight pair on the c5- and e5-outposts. 12... d8b6  13. e5f3 A strong reaction $1 13... e7e6  14. c3a4  14... b6d6  15. d1d2 Aronian's opening choice was a huge success. He managed to smother the opponent's light-squared bishop and is in full charge of the dark-squares. 15... a6a5  16. a1c1  16... c8d7 Keymer was counting on this natural development to force the active knight back, but he was about to be unpleasantly surprised. 17. a4c5  17... b7b6 It seems the knight needs to retreat... 18. g5f4  18... d6e7  19. c5d7 But no, Aronian plays instead in the spirit of the famous Fischer-Petrosian game and is voluntarily parting with his amazing knight. 19... f6d7  20. c1c7  20... f8c8  21. e1c1  21... e7d8 