France coach Didier Deschamps on Thursday announced that defender Raphael Varane had missed training and was doubtful for his team's World Cup qualifying play-off first leg against Ukraine in Kiev.
"His knee is swollen and is a worry," Deschamps said at an eve-of-game press conference.
"Yesterday (Wednesday), he was receiving treatment and has not trained with the rest of the squad. It will be the same today (Thursday).
"We will make a decision on the day of the game."
France's medical staff had said on Wednesday that the young centre-back was following the same programme to that employed by the staff at Real Madrid as he recovers after undergoing right knee surgery in May.
The 20-year-old, who has three caps, had also sat out training prior to last month's friendly against Australia, although he did play in the 6-0 win at the Parc des Princes.