"The lad's not getting any luck at all at the moment," United boss Sir Alex Ferguson said.
"He came down on his ankle in the reserve game last night and he'll be out for six to eight weeks. It's ligament damage.
"He was coming on fantastically well. He was training really well. I made him substitute on Wednesday (against Villarreal) as an indication of his return to fitness.
"He's a top goalkeeper. I just hope he gets a little break now, get over this one and hopefully he won't get any more unfortunate injuries.
"This is nothing to do with his previous injury of course, where he had a cruciate knee injury, it's just bad luck."