Defender Rio Ferdinand will miss Manchester United's Premier League showdown with Chelsea on Sunday as he continues to be troubled by a calf injury.
Ferdinand has missed United's last three matches with a calf injury which manager Sir Alex Ferguson believes could be linked to the defender' long-running back problems.
"We don't know where the calf injury is coming from. It could be the lower back," he explained ahead of the trip to Stamford Bridge.
"A calf injury usually means two to three weeks out. But there's no sign of recovery from that injury.
"We're looking at whether it's coming from his back, but in the meantime he's out. There has been no improvement, so obviously we're looking at something different."
However, United will welcome back both of Nemanja Vidic and Dimitar Berbatov after they missed the midweek 3-3 Champions League draw with CSKA Moscow.
Midfield duo Ji-Sung Park and Owen Hargreaves remain absent through injury while club captain Gary Neville is suspended.
"Vidic has trained for the last three days and he should be okay for Sunday," said Ferguson.
"Berbatov got knock and we'll see what he's like in training today but he should be okay.
"Rio and Park are both out and Gary is suspended of course. Other than that, the rest are fit and we're ready for a big game."