Manchester United midfielder Ander Herrera is in danger of missing Saturday's match against Aston Villa because of a knock.

The 26-year-old suffered the problem during his side's 2-1 victory over West Ham United in their FA Cup quarter-final replay on Wednesday.

Herrera was replaced during the match by Morgan Schneiderlin, and manager Louis van Gaal has claimed that he is unsure whether or not the midfielder will be fit tomorrow.

"At this moment, I don't know, as the diagnosis is still yet to come," Van Gaal told reporters in Friday's press conference. "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."

United's last Premier League game ended in a 3-0 defeat to Tottenham Hotspur at White Hart Lane.