A cautious move. Grischuk  makes sure there will be no long-ranged pieces eyeing his king.
1. d2d4  1... g8f6  2. c2c4  2... e7e6  3. b1c3  3... f8b4  4. g1f3  4... d7d5  5. d1a4  5... b8c6  6. e2e3  6... e8g8  7. a4c2  7... b7b6  8. c1d2  8... c8b7 This leads to an already fresh position. According to my  Megabase only two games have been played in the line. 9. a2a3  9... b4d6  10. c4d5 The first lenghthy thought by the Chinese player. 10... e6d5  11. f1d3  11... a7a6  12. c3e2 This novelty has been played after  almost half an hour of thought. 12... c6e7  13. d2c3 Xu stops the c7-c5 advance... 13... f6e4 ...but allows another unpleasant move. If the knight is  left where it is the kingside attack will run smoothly. 14. d3e4  Therefore White ventures into a risky line. 14... d5e4  15. f3g5 Black loses a pawn, but in the process all his  long-ranged pieces are freed.