The £30m summer signing from Villarreal had been the pick of Mourinho’s signings and was named the club’s player of the month in August.
However, he suffered a knee ligament injury during the 4-0 defeat to Chelsea last month, leaving Mourinho with a depleted defence while fellow centre back Chris Smalling is also out nursing a broken toe.
That has left Phil Jones, who has just come back from a series of long-term injuries, and Marcos Rojo filling in with Daley Blind providing cover for the pair.
Bailly had been expected to miss most of December as well but it looks as though he will be fit much sooner than expected, although he will definitely not be available for the EFL Cup tie with West Ham on Wednesday night.
However, he could be available for the December 11 Premier League clash with Tottenham at Old Trafford.
Mourinho hinted at Bailly’s comeback last week, saying: “He is working hard and will be back before the end of the year, for sure."
The news is not completely positive though, with Bailly’s return to fitness meaning he will likely be unavailable for the majority of January when he joins up with the Ivory Coast for the Africa Cup of Nations.
United have been linked with a move back into the transfer market in order to cover Bailly’s absence, with Southampton pair Jose Fonte and Virgil van Dyke among Mourinho’s targets.
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies