I suffered a bad loss in a Sicilian mainline recently when I ran into an opening novelty that I was unprepared for. The move should not present White with serious problems but you might want to look in to this in case you face it over the board:
1. e4 c5 2. Nf3 Nf6 3. Nc3 Nc6 4. d4 d5!?
My game continued:
5. exd5 Nxd5 6. Bc4 Nb6 7. Bb5 cxd4 8. Nxd4 a6 9. Nxc6 Qxd1+ 10. Kxd1 axb5 11. Nd4 b4 12. Nce2? after which I got into trouble (Ncb5 is better).
After the game my opponent told me that IM Jon Rowson won as White in the line 6. dxc5 Nxc3 7. Qxd8+ Kxd8 8. bxc3. Despite the extra pawn I’m not attracted to White’s structure but who am I to argue with an IM?