The 26-year-old left the King Power Stadium on crutches yesterday after he picked up a leg injury during United's 5-3 defeat to Leicester City.
Despite United showing their defensive woes in Sunday's game, Van Gaal believes that he can call on Luke Shaw, Marcos Rojo and Chris Smalling should Evans be ruled out of this weekend's game against West Ham United.
"He got a kick," the Daily Mail quotes Van Gaal as saying. "I don't know how bad it is. We have to wait and see. He's on crutches. I think Shaw shall be fit enough to play and Rojo and Smalling can play. We can manage."
United have lost two of their five Premier League games this season.