Test have confirmed that Barcelona star Samuel Eto'o has torn the meniscus in his right knee and will be sidelined for up to three months.
The Cameroon striker sustained the injury in Barca's 1-1 UEFA Champions League draw with Werder Bremen on Wednesday night.
He was stretchered off just past the hour mark having collapsed following a sharp change of direction.
Barca were hoping he had merely strained ligaments, but subsequent tests have revealed the full extent of the injury and the 25-year-old will now undergo exploratory surgery to correct the problem on Thursday afternoon.
"The club's medical services carried out a scan on Eto'o's knee this morning and confirm that he has torn the meniscus in his right knee," read a statement on Barca's official website.
Eto'o looks likely to be out of action for between two and three months, meaning he will almost certainly miss the remainder of Champions League group stages as well as several league games.
The news will come as a hammer blow for the Catalans for whom the African has bagged over fifty goals since his switch from Mallorca in the summer of 2004.