An excellent reaction. White had many options, but this is the most accurate.
1. e2e4  1... c7c5  2. g1f3  2... e7e6  3. g2g3 White can build an entire repertoire with Anti-Sicilians alone and still fight for an advantage in the opening. Against 2...d6 or 2...Nc6 one of the main alternatives is to place the bishop on b5, and against 2...e6 White can try the move played of the game, fianchettoing the bishop (suggested by Wesley So in his Chessable course), but he can also play 3.d3 (King's Indian Attack) or 3.c3, with a version of the Alapin in which Black has slightly fewer possibilities than normal. Even 3.b3 is a possible try. 3... b8c6  4. f1g2  4... g8f6  5. d1e2  5... d7d6  6. e1g1  6... f8e7  7. c2c3  7... e6e5  8. f1d1 The most critical idea: White aims for a quick d2-d4. 8... e8g8  9. d2d4  9... c5d4  10. c3d4  10... c8g4  11. d4e5  11... c6e5  12. b1c3  12... d8c8 A new move. Grischuk stops h2-h3. 13. c1f4  13... c8e6  14. d1d2 White prepares to get out of the pin using the tactical idea of ​​placing the knight on d4. 14... a8c8  15. f3d4  15... g4e2 The alternatives are worse: 16. d4e6 Now the rook on f8 is attacked and Black has no option but to capture the knight. 16... f7e6  17. c3e2 Now Black needs to be fast, as White has a long-term positional advantage with the bishop pair and better pawn structure. 17... f6g4 A tempting move, but not the best.