The center back will miss an undetermined amount of time as he receives treatment on the injury that has plagued him throughout the season.
Manchester United manager Jose Mourinho has revealed that the ankle problem currently being nursed by key defender Eric Bailly is 'serious' and could soon require surgery if the treatment he is receiving offers no improvement.
Bailly has already missed United's last eight games in all competitions due to the ongoing problem and it remains to be seen how much longer he could be out for if surgery is the answer.
"I think his injury is serious," Mourinho explained to the media following Wednesday night's narrow home win over Bournemouth.
"I don't know [how long he will be out] but his is an injury that comes from the last time he went with the international team and then we are trying a conservative treatment," the boss added.
"But, if the conservative treatment is not resulting, probably he will have a surgery procedure but let's wait a little bit more."
Mourinho could offer little on the specifics of the injury when quizzed further, stating in no uncertain terms, "I'm not a doctor," but doesn't believe Bailly's season is over.
"I don't want to be so pessimistic. I want to leave it with the doctor," he said.
The Portuguese coach is also unconcerned about what it means for his center back options in the coming weeks. Chris Smalling, who has come in for special praise from Mourinho following his recent performances, partnered Phil Jones on Wednesday, but Marcos Rojo is set to be available again at the weekend after recovering from a head wound.
Victor Lindelof and even Daley Blind are other center backs highlighted by the manager.
"During the whole season, we've had problems with central defenders but because the number is four or five, we manage always to have [players available] and Chris Smalling is playing amazingly well for seven or eight matches in a row maybe, so we are fine," Mourinho stated.