Ole Gunnar Solskjaer is worried Marcus Rashford could be sidelined after injuring his groin in Sunday's 2-0 loss to West Ham United.
The England international was substituted after 60 minutes when he suffered a muscle injury.
"We have got to scan him tomorrow," Solskjaer said after the match.
"He felt his groin. So he will probably be out for a little while. I can update you later when I know a little more."