France skipper Thierry Dusautoir has been ruled out of at least two of les Bleus' three November Tests.
Dusautoir injured his knee in Toulouse's Heineken Cup win over Treviso on Saturday and is set to be sidelined for six weeks, meaning he is sure to miss France's clashes Australia on November 10 and Argentina the following weekend.
He is also in serious doubt for the clash against Samoa at the Stade de France on November 24.
"Thierry suffered a twisted internal lateral ligament with a slight tear," said Toulouse manager Guy Novès.
"It's an injury that necessitates between four and six weeks rest depending to his ability to properly recuperate."
France are expected to name a replacement for Dusautoir on Monday. Stade Français lock Pascal Papé is likely to take over the captaincy.