Manchester United must make do without star midfielder Shinji Kagawa for up to a month after he suffered a knee injury in midweek.
He twisted his knee during the first half of Man United's 3-2 UEFA Champions League victory against SC Braga on Tuesday.
"I think playing on with the injury did not help the situation for him, even though he did well to play on with it. It's disappointing for him," said Manchester United manager Sir Alex Ferguson.
Chelsea star Frank Lampard will miss at least two weeks with the calf injury he picked up during his side's UEFA Champions League defeat at FC Shakhtar Donetsk on Tuesday.