MANCHESTER -- Eric Bailly is facing a race against time to be fit for Manchester United's Champions League knockout tie with Sevilla after being told he must have surgery to correct an ankle injury.
The defender, 23, has missed United's last eight games, last appearing in the 1-0 defeat to Chelsea at Stamford Bridge on Nov. 5.
United's medical staff had hoped Bailly, who picked up the problem while on international duty with Ivory Coast, would respond to treatment and not require an operation.
But after failing to make any progress, it has been decided the centre-back does require surgery, which could now keep him out for up to three months.
"Bailly goes to surgery -- the decision is made," Mourinho told MUTV. "I don't say [he's out] for the rest of the season but it's for the next two or three months.
"But now we have [Phil] Jones back and we have [Chris] Smalling, even [Daley] Blind, so it's a position we have good cover in but of course we'll miss the player."
It means Bailly is facing a battle to be ready for United's trip to Sevilla in the Champions League round of 16 on Feb. 21.
He will almost certainly miss the trip to Wembley to play Tottenham on Jan. 31.
United travel to Spain to face Sevilla, currently fifth in La Liga, before Chelsea visit Old Trafford on Feb. 24.
They play Liverpool at home on March 10, three days before Sevilla travel to Manchester for the return leg on March 13.