Roma have received a huge blow ahead of Sunday's derby with Lazio as inspirational forward Mohamed Salah was ruled out with an ankle injury, Sky Italia confirmed on Thursday.
The Egyptian international winger had to pull out of Wednesday's training after colliding with teammate Thomas Vermaelen.
Salah came to the ground on Thursday morning but was unable to train. He later underwent MRI scans to determine the extent of the injury.
Roma is waiting for scan results to assess the length of Salah's absence.
On Wednesday, the assistant coach of the Egyptian national team, Osama Nabih, told local media that Salah's injury is minor, adding he would be fit in time for the 2017 Africa Cup of Nations that will kick off on 14 January.
The 24-year old Salah has been one of Roma's key players since initially joining them on loan in the summer of 2015 before making the move permanent at the beginning of this season.
He has scored eight goals and contributed four assists in the Serie A so far this term.
Roma are second in the league table with 29 points, four behind leaders and defending champions Juventus.
