Michael Carrick has been ruled out for three weeks with an Achilles injury.
The Manchester United midfielder had an injection yesterday after informing Sir Alex Ferguson the long-standing problem was starting to bother him once more.
"He should be out for three weeks, maybe a month at most," said Ferguson.
It means Carrick will miss tomorrow's visit to Everton, plus the home matches with Rangers and Liverpool that follow in a busy week.
However, Ferguson will have Rio Ferdinand available for the first time this season after the defender made a quicker than expected recovery from the knee injury he suffered on the first day of World Cup training in South Africa.
"Rio Ferdinand could have played for the reserves against Stockport last night," said Ferguson.
"He wanted to play but his training performances are so good I didn't see any point.
"He is in the squad. With three games this week, it is good that he is back in the fold."
