Manchester United midfielder Anderson has been ruled out until February due to a knee injury but Wayne Rooney is set to face Newcastle United on Saturday.
Anderson has been sidelined since picking up the problem in the UEFA Champions League victory over Otelul Galati at the start of the month.
The Brazilian's injury was not thought to be a long-term issue, but Sir Alex Ferguson has revealed the former Porto youngster has travelled to Portugal to see a specialist.
Ferguson is not expecting to have the 23-year-old, who missed a large part of 2010 with a knee injury, back in his plans until well into the New Year.
He had formed a blossoming partnership in the centre of midfield with Tom Cleverley during the early weeks of the season, but Ferguson is now without both players.
Cleverley is currently sidelined by an ankle ligament injury, but Ferguson feels the England hopeful could return before the festive period.
However, despite losing two of the younger members of his midfield to injury, Ferguson is still satisfied with the options at his disposal.
"Anderson is not fit until February," said Ferguson. "He's gone to see a specialist in Portugal about his knee.
"We didn't expect that and it's a blow.
"Cleverley is the other midfielder out for a while now. But we're not as bad as people think we are in midfield with the experience of Giggs, Carrick and Fletcher, and if we get Cleverley back for Christmas, that'll be a bonus."
Ferguson, though, has received a boost after confirming he expects leading scorer Rooney to be fit for the game against Newcastle.
Rooney sat out the UEFA Champions League draw against Benfica in midweek with a hip injury sustained in last weekend's win at Swansea City.