Mourinho finished 6th last season with the Mancunian club, but went on to win the Europa League, and therefore, qualified for the Champions League this season. "I don't say (he's out) for the rest of the season but it's for the next two or three months".
It has been more than a solid season to the campaign for United, however, their bitter city rivals Manchester City have been on another level this season, with Pep Guardiola's side having an 11-point gap at the top of the Premier League.
"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 worldwide team and then we are trying a conservative treatment".
Bills confirm Tyrod Taylor (knee) will start against Miami
The only player who has been ruled out for the game is guard John Miller, not a surprise as Miller hasn't played since the first half of the season.
"Especially players who belong to other clubs".
Mourinho has also revealed that he is unlikely to make a major move in the January transfer window when it opens in a little over two weeks' time although the United manager would not rule out the possibility entirely.
'I don't like the January market just to buy (for the sake of buying).
"I think it's serious", Mourinho said in his press conference. If you ask me one thing that I don't like a lot, it's that they lose balance very easily.