The Red Devils skipper was unable to help the 20-time English champions avoid a 2-1 defeat by Premier League strugglers Sunderland at Stadium of Light on Saturday afternoon.
He has a knee problem so we have to wait and see
Louis van Gaal
Rooney suffered the injury during the loss to the Black Cats and won’t feature in the first leg of United’s Europa League last-32 clash against FC Midtylland in Denmark on Thursday night.
Speaking to United’s website on Wednesday, Van Gaal confirmed Rooeny’s injury blow ahead of United’s Eurpean clash.
“We have 13 players out and Wayne is one of them,” Van Gaal said.
“You can never say [how long he could be out for]. He has a knee problem so we have to wait and see.”
The United captain has been influential for the Red Devils so far this season after a return of five goals and three assists in 2016.
And Van Gaal admitted that the 30-year-old would be a big miss for his side.
“He scores a lot of goals so he is very important for us. We know that but we have to cope,” Van Gaal added.
Rooney has scored seven goals and has made four assists in 22 Premier League games so far this season.
The United boss also revealed that Matteo Darmian and Cameron Borthwick-Jackson are also sidelined for their Europa League clash.
“Darmian has a dislocated shoulder. It’s not the heaviest type so we are lucky, but he is injured and out,” Van Gaal continued.
“Borthwick-Jackson is ill and cannot play either, so we have 13 players injured or not capable of playing.
“I have never had that amount of players injured [before]. When you realise that they are only contact injuries – only Marouane Fellaini maybe has a muscle problem, the rest have contact injuries – it’s unbelievable that we are very unlucky.”
MORE: The latest football news