Ander Herrera is a doubt for Manchester United's Premier League clash with Aston Villa after picking up an injury in midweek against West Ham.
The Spaniard sustained the knock late in the second half of United's 2-1 FA Cup quarter-final replay success at Upton Park and, after being forcibly carried off by Mark Noble, was replaced by Morgan Schneiderlin.
In his pre-match media conference on Friday, manager Louis van Gaal did not think the problem was too serious, but was unable to give a definitive update on Herrera's condition.
"At this moment, I don't know, as the diagnosis is still yet to come," he said.
"It is better to do that after two days, so I haven't heard about him yet. It is not so heavy we think, but we have to wait and see."
Van Gaal lamented United's chronic injury woes this season, although he was able to give positive updates on Wayne Rooney and Luke Shaw.
"That [injuries] is a continuing problem, because we have to play so many matches when you are in so many competitions during this season, that is the only problem," he told MUTV.
Rooney made a brief comeback against West Ham on Wednesday after two months out with a knee injury, while Shaw has been out since breaking his leg in September.
"He [Rooney] always wants to play. Yes, I think he shall receive more minutes [against Villa] but it's always dependable on the game," Van Gaal told MUTV.
"You cannot say in advance that I give you 20 minutes or something like that; when it's possible, I shall do that because we need Wayne in the team.
"Shaw is now training on the pitch with the physiotherapist, it's not with a trainer-coach, so that's the difference. But he's going great, it's unbelievable."
However, there was less good news on the condition of Bastian Schweinsteiger, who is struggling with a knee problem.
"I don't think Schweinsteiger shall play this season - I think, next season, he is prepared. Maybe he is prepared for the European Championship, I cannot predict," he said.
"It is possible, but then that is also in our favour because then he is fit for the new competition."