Manchester United face an early season injury crisis.
Boss Alex Ferguson said: "You worry about having a team ready for the start of the season. I doubt if we'll have Wayne fit for the start.
"It's a virus we believe he picked up in Nigeria. It's not a nice one. It's such a bad virus that he's not been training since we got back from Africa on July 28.
"The league season starts in 12 days' time and he's gone a long time without training.
"Carrick also had the virus but, hopefully, he'll play some part against Portsmouth in the Community Shield on Sunday."