Another interesting line proceeds: 1. e4 c5 2. Nf3 d6 3. d4 cxd4 4. Nxd4 Nf6 5. Nc3 Nc6 6. Bg5 e6 7. Qd2 a6 8. O-O-O Bd7 9. f4 b5 10. Bf6 gf6
11. f5!?.
11f5!? is covered by Kanmazalp in his course at modern chess. Kozul does not cover it directly, but transposes to a variation. Black can either try to transpose to other lines with 11...Qb6, or play uniquely with 11...Nxd4 followed by 12...Bh6ch.
After
11...Qb6 12. Nc6 Bc6, white can trade pawns with 13. fe6 fe6. Then 14Kb1 Qc5 15. Bd3!? h5 reaches a position covered by Kanmazalp and Kozul (chapter 8 section 4). Players have alternatives along the way and subsequently. After 16Qe1!? Qe5, 17Nd5!? is a sacrifice that the engine initially considers very strong, then perhaps about equal.
The other way to proceed is 11...
Nd4!? 12. Qd4 Bh6ch 13. Kb1 Bf4 14.fe6!? fe6 15. Ne2 Be5 16. Qd2 (other queen moves may also be possible).
I like black's centralized bishop, but his position has weaknesses. Kanmazalp analyzes from this position.
I have the impression that 11f5!? is no longer fashionable. However, players of the black pieces must consider it, and player's of the white pieces might choose to look at it as well.