Manchester United captain Nemanja Vidic will be out of action for two months after undergoing knee surgery, the Premier League club said on Tuesday.
The Serbian defender missed six months of last season with knee ligament damage before returning to the first team at the start of the current campaign.
"Nemanja Vidic has had a meniscus operation on his right knee and will be out for around eight weeks," United said in a statement on their website.
"Sir Alex (Ferguson), as a precautionary measure, rested Vidic at the weekend, after he complained of tightness in his knee, however, further medical investigation revealed the underlying problem.
"The central defender was operated on this week and will be sidelined for about eight weeks."
The loss of the 30-year-old Vidic is a further blow for Ferguson who was already without defenders Phil Jones and Chris Smalling through injury.
United have won four of the first five Premier League games of the season but have looked vulnerable defensively, with Rio Ferdinand and Jonny Evans now the only experienced centre backs who are fit.