Lyon defender Francois Clerc is set to be sidelined for around six months with a knee injury.
Clerc ruptured the anterior cruciate ligament in his left knee during the first half of his club's 3-0 win over Toulouse in Ligue 1 on Sunday.
"Francois Clerc had a MRI scan this morning which revealed the seriousness of his injury," the French club confirmed on their official website.
"He will be out between five and six months."
If Clerc is not able to return until early 2009 it means he will miss the first half of Lyon's Ligue 1 campaign.
Lyon will also be without the 25-year-old for the group stages of the UEFA Champions League, while France will not be able to call on him for their upcoming World Cup qualifiers.
Clerc has established himself as a regular member of the France squad in recent months and made his 13th international appearance in the defeat to Italy at Euro 2008.