Steve Sidwell has been ruled out until Christmas and Aston Villa team-mate Nigel Reo-Coker is likely to be sidelined for three weeks.
Midfielder Sidwell has been struggling with an Achilles problem and put surgery on hold prior to the local derby against Birmingham City last month.
Villa have already lost captain Stiliyan Petrov until next year due to a knee injury and the club were trying to nurse Sidwell through.
However, Gerard Houllier has confirmed the former Reading man now requires an operation and he will be out until the festive period.
"Steve Sidwell will have an operation," said the Villa boss. "You remember at some stage he was about to have it and had to delay it.
"But his Achilles tendon has flared up again so the best thing is to do it now - as soon as possible.
"We will be hoping he will be back for the Christmas period when it is very busy."
Meanwhile, acting captain Reo-Coker will be out for up to three weeks after suffering a knee injury in the weekend draw at Fulham.
Houllier added: "Nigel is not as bad as we thought. He could be back in training in two to three weeks.
"We thought it was a tear, but it is just slight damage to the medial ligament. That is good news."
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