Jose Mourinho believes Romelu Lukaku is likely to miss two matches after sustaining a head injury in the goalless draw with Southampton on Saturday.
Lukaku clashed heads with defender Wesley Hoedt after just eight minutes at Old Trafford and consequently made way for Marcus Rashford.
The Belgium international received treatment on the pitch for several minutes before leaving the field on a stretcher.
And while Mourinho remains uncertain of the extent of Lukaku's issue, he does not expect to have him available for Monday's trip to Everton or the FA Cup clash with Derby County.
"I don't know," he told a news conference. "I know that normally bad, bad news arrives immediately and bad news didn't arrive.
"But to leave the pitch the way he did, we don't think twice to make that decision immediately. It's because there is a problem not just for today but the next two matches I would say, for sure."
The loss of Lukaku comes as an added blow to Mourinho, who earlier confirmed Zlatan Ibrahimovic would miss a month of action with a knee injury.
Get the best features, fun and footballing frolics straight to your inbox every week.
Thank you for signing up to Four Four Two. You will receive a verification email shortly.
There was a problem. Please refresh the page and try again.