Rangers manager Paul Le Guen fears Lee Martin will miss next week's Uefa Cup trip to Livorno with a knee injury.
Le Guen:
"He has been troubled by this for three weeks after taking a knock on his knee and I am little bit worried by this.
"Our doctor will work in conjunction with Manchester United."
Rangers are already without injured wide players Chris Burke and Libor Sionko for the Uefa Cup group stage opener in Italy on 19 October.
"Lee Martin has a problem with his knee, which is a bit worrying and it leaves us short of wingers," Le Guen told Rangers World.
"It is bad luck, but we must keep our head up and keep working."