Chelsea look set to be without Michael Essien for the rest of the year after it was confirmed the midfielder would need surgery on a knee injury.
The 25-year-old suffered the problem while on international duty and was stretched off in the game between Ghana and Libya on Friday night.
He had missed the start of Chelsea's Premier League season because of injury and had only recovered last week.
A club statement read: "Michael has ruptured his anterior cruciate ligament and will undergo an operation as soon as the majority of the swelling has subsided. We expect this to happen in a week's time.
"In the meantime, Michael has started rehab in the aqua therapy centre at Cobham which will improve the condition of the knee prior to surgery. A return to full fitness is not expected for several months."
Essien's agent Fabian Piveteau has confirmed that it's a serious problem for the former Lyon man.
Piveteau said: "Unfortunately it's not good news. I am afraid it's a big problem. A big problem.
"He's taken a bad blow to the knee. I don't know exact details but I think it's not good. I don't know what will happen. It's now two or three times that he has taken blows to his knee."
Essien has become a key figure for Chelsea since signing from Lyon for £24 million three years ago and the loss of the combative Ghanaian for such a long period is a major blow to the Blues, who have no like-for-like replacement available and will not be able to buy any fresh faces before the transfer window re-opens in January.
Luiz Felipe Scolari's men - who opened the new campaign with two wins and a draw - are in Premier League action away to Manchester City on Saturday before then embarking on their European campaign at home to Bordeaux and a clash with champions Manchester United on September 21.