comment: A good reaction, pinning the knight and exerting pressure on the center.
context: 1. g1f3  1... d7d5  2. g2g3  2... g7g6  3. d2d4  3... f8g7  4. c2c4  4... c7c6  5. f1g2  5... g8f6  6. e1g1  6... e8g8 The system with c6-d5 in the Grunfeld Fianchetto has been played in thousands of games, even at the world championship level. It's one of Black's most solid options. 7. f1e1 A big surprise. I've never seen this move before. Can you imagine this is only the 15th most-popular move in the position $2 It was played by a GM just twice before, both times in blitz games. So it's safe to say that this is nearly a new idea. 7... d5c4 A principled reaction, played after a long reflection. One feature of Ding's style is that he's not afraid to go for complicated and forcing variations, even when he might face advanced preparation. 8. e2e4 Officially a new move. This is obviously White's idea 7.Re1.