Juventus striker David Trezeguet will have to undergo surgery after a scan revealed the extent of his right hamstring problem, which was aggravated during Wednesday's 1-0 Champions League win against Zenit St. Petersburg.
The French striker, who turns 31 next month, underwent tests on Friday to assess the extent of the injury.
A club statement confirmed the diagnosis: "The tests showed that his hamstring will need to be operated on."
Trezeguet played 87 minutes of the match against last season's UEFA Cup winners.
It is not yet known how long he will be out of action, but he is likely to miss Juve's next few Serie A matches and the European match at BATE Borisov on 30 September.