In the line 1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 a6 6. Bg5 e6 7. f4 Nbd7 8. Qf3 Qc7 9. O-O-O b5 10. Bd3 Bb7 11. Rhe1 Qb6 12. Nd5 Qxd4 13. Bxf6 gxf6 14. Bxb5 Qc5 15. b4 Qxb5 16. Nc7+ Ke7 17. Nxb5 axb5 18. Qd3 Ra6 19. Qxb5 Rb6 20. Qd3 Bh6 21. g3 



I was following line b in the note to White's 15th move on p. 87 of Rizzitano's Najdorf book. What is the best move on move 21 for Black now? I saw the game Ootes-Van Kampen, Twente 2010, where Black played 21...Rc8 22. a3 Ne5, I suppose the idea to establish an outpost on the queenside whilst protecting both the rook on b6, which also protects the d6-pawn.