Manchester United striker Wayne Rooney could miss two months of the season with a knee ligament injury, according to The Times.
Rooney was already set to miss United's match against FC Midtjylland in the Europa League on Thursday, having not been named to the 18-man travelling squad for the first leg of the round-of-32 tie.
The club did not explain the forward's absence, and manager Louis van Gaal confirmed he had a knee injury but would not say how long Rooney would be out.
More on Rooney from the boss: "You can never say [how long he could be out for]. He has a knee problem so we must wait and see." #MUTV #mufc
- Manchester United (@ManUtd) February 17, 2016
"Certainly in 2016, he has scored, and that's why we had a good run in matches until Sunderland," Van Gaal said. "But we have to cope with that. Everybody can be injured, and also the captain can be injured.
"He's a guy who wants to go until the end, and if he is feeling pain, he doesn't want to go away, and certainly when you are drawing a match, because he wants to win. That's a fantastic attitude, but also it's bad for his body. You do not know when it happened, so that's the difficulty."
The 30-year-old had rediscovered his form recently after a disappointing start to the campaign, scoring seven times in nine appearances since Jan. 1.
A prolonged absence for Rooney would test Manchester United's attacking resources, which have been questioned this season. Responsibility will fall on the shoulders of Anthony Martial, while Will Keane was named to the squad for the visit to Denmark.
The news is also a blow to England ahead of the European Championship in the summer. They have friendlies against Netherlands and Germany in March that their captain is now expected to miss.
With at least 12 senior players not available for the Midtjylland match, Van Gaal has called up several young, inexperienced players such as Donald Love, Regan Poole, Joe Riley, James Weir and Keane.
"When you analyse the injuries, it's ridiculous," Van Gaal said. "They are all contact injuries, and it is a lot of bad luck. Maybe once or twice you have to back up the team with youngsters, but this year we have had to do it every week. But we have seen that it's also beneficial for Manchester United.''