Crystal Palace boss Roy Hodgson has bemoaned the injury suffered by Patrick van Aanholt.
The Palace left back suffered a shoulder injury after he tangled with Anthony Martial, in the move where Martial scored to give Manchester United a 2-0 win on Thursday.
He has a dislocated shoulder and will have a scan on Friday.
"It's a bad injury and it's going to keep him out for a long period," Hodgson said to reporters.
"They'll look at it tomorrow [by running a scan] and find out what the next step will be for him.
"I think he'll require an operation and that's bad news for us. Patrick has been solid for us, he's had a good season, he's hardly missed any games and now we might start next season without him."