The embattled captain suffers from an ankle injury he picked up during the 1-1 draw with the high-flying Leicester City last weekend, while fullback Rojo suffers from a repeat of the shoulder dislocation he had last season.
Speaking to the club’s website, the Dutch tactician revealed:
"Wayne's injury is more heavy than we thought and it's a nasty injury.''
"When we go on it's been getting worse. We have to let him train to make the ankle stronger, that's very important.''
Speaking about Rooney's return from injury, Van Gaal added:
"I cannot say because the doctor shall decide that with Wayne of course. He is training well in the rehabilitation."
Marcos rojo clears the ball in a previous league match for Man United. The 25-year-old has a recurrent shoulder problem that will keep him out of action this weekend.
On the other hand, Rojo is suffering from a dislocated shoulder and the former Ajax boss did not seem happy about it:
"Rojo has been injured. It's his shoulder, the same as last year, in a training session. It's very unfortunate, also in the position of Luke Shaw so I have a great problem."
"I have already given the players two days off this week. I am giving them a lot of rest because I think it is necessary now, nevertheless we have six injuries most of which are contact injuries.''
"You cannot avoid those because football is a sport with direct resistance. We are unlucky I have to say."
Other players on the injury list include Phil Jones, Ander Herrera and the sensational Jesse Lingard.
The Red devils are currently third on the Premier League table with 28 points, while the Hammers are eighth with 22 points. A win for Van Gaal’s men could take them to the top of the table if Leicester City and Manchester City fail to collect maximum points in their respective fixtures.
