Played after a long think. This is an important position for opening theory.
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.