Lyon right-back Francois Clerc has been ruled out of action for up to six months with a knee injury.
The France international limped off midway through the first half of Les Gones' 3-0 win over Toulouse in Ligue 1 on Sunday.
An MRI scan taken on Monday revealed Clerc has ruptured anterior ligaments in his left knee and will not return before the winter break.
A Lyon statement read: 'His unavailability is estimated at between five and six months.'
The injury will come as a blow to France coach Raymond Domenech, who selected Clerc in his Euro 2008 squad earlier this year.
With Willy Sagnol also currently injured, Domenech is short of experienced right-backs and is now expected to select Arsenal's Bacary Sagna and Anthony Reveillere, Clerc's team-mate at Lyon, in the squad for next week's friendly against Sweden.
Les Bleus' 2010 World Cup qualifying campaign begins in September with an away match against Austria on September 6.
Clerc, 25, has established himself as Lyon's first-choice right-back over the past two years, regularly being selected ahead of Reveillere in the position.
Two players, centre-back Cris and goalkeeper Gregory Coupet, suffered knee-ligament injuries while playing for Les Gones at the start of last season.
Clerc's injury may prompt coach Claude Puel to dip into the transfer market in search of a back-up for Reveillere.