Bailly has not appeared for Manchester United since their 1-0 defeat to Chelsea at Stamford Bridge in October.

The Ivory Coast defender was expected to return in mid-November but his comeback was delayed.

And speaking after United’s narrow 1-0 win over Bournemouth, Mourinho described Bailly's injury as "serious”.

He then added that an operation was an option if "conservative treatment" didn’t work.

United remain 11 points off City in the table as a result of their win but were once again indebted to goalkeeper David de Gea, who made key saves to deny Bournemouth.

And Mourinho expressed his relief with the win.

He told Match of the Day: “I am pleased with the three points, it was difficult match. 

“They had one more day’s rest than us, they were fresher than us, and mentally fresher because a big match takes more from our players.

“We had chances, Martial missed a good chance, Rashford could have had an astonishing effort, and in the last 15 they pushed us.”