Mysterious rook move in the Grunfeld [FEN "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1"]

1. c4 g6 2. d4 Nf6 3. Nc3 d5 4. Nf3 Bg7 5. cxd5 Nxd5 6. e4 Nxc3 7. bxc3 c5 8. Be3 Qa5 9. Qd2 Nc6 10. Rb1 a6 11. Rc1


In this line of the Grunfeld, White has played 10. Rb1 followed by 11. Rc1. Why? If White wants the rook on c1, why not just play 10. Rc1? What is the benefit of provoking 10...a6 first?
Peter Svidler explains this in his excellent video series and e-book on the Grünfeld (Premium access only).

The point is the initiative. This move discourages black from playing 11...cxd4, because that would lead to a very uncomfortable situation for black: After 12.cxd4 Qxd2+ 13.Kxd2 O-O 14.d5 Rd8 15.Ke1, there is no good square for the knight. 15...Na5 is now impossible, because the bishop can go to b6.

And this is the reason why Svidler follows Avrukh's recommendation to play 11...Bg4 in this case.

[ECO "D85"]
[Opening "Grünfeld Defense: Exchange Variation"]
[FEN ""]

1. d4 Nf6 2. c4 g6 3. Nc3 d5 4. cxd5 Nxd5 5. e4 Nxc3 6. bxc3 Bg7 7. Be3 c5 8. Nf3 Qa5 9. Qd2 Nc6 10. Rb1 a6 11. Rc1 cxd4 (11... Bg4 { Recommended by Avrukh and Svidler } 12. d5 Rd8) 12. cxd4 Qxd2+ 13. Kxd2 O-O 14. d5 Rd8 15. Ke1 Nb4 (15... Na7 { Best move according to Stockfish. Has never been played. })  (15... Ne5 16. Nxe5 Bxe5 17. f4 Bb2 18. Rc2 Ba3)(15... Na5?? 16. Bb6!) 16. Bd2 a5 17. a3 Na6 *