France prop Sylvain Marconnet faces a race against time to be fit for the World Cup after being told he will not return to training before August.
Marconnet has featured in all three of France's Six Nations wins so far
The 30-year-old fractured his fibula and tibia in a skiing accident at the weekend and had surgery on Tuesday.
Marconnet, the most capped French prop with 71 appearances, will be out of action for at least five months.
"The fracture was big and to recover completely, it is six months," said Marconnet's surgeon Philippe Landreau.
"Fortunately, it is not an open fracture.
That Sylvain will have recovered in six months, I have no doubt. But what state will he be in?
Surgeon Philippe Landreau
"For a simple fracture, it is three months out. After a fracture like this one, in order to have a proper strengthening of the bone, it is a minimum three months, but perhaps more."
France play the opening game of the World Cup against Argentina in St Denis on 7 September.
Head coach Bernard Laporte is set to name his squad for the tournament on 3 August although that could be brought forward.
Marconnet is likely to miss the three warm-up Tests before the start of the World Cup, against England on 11 and 18 August and Wales in Cardiff on 25 August.
"Sylvain should be back in training at the start of the fifth month, not before. In this case, that leads us to the start of August," added Landreau.
"But to recover completely, it is six months. And six months - that is when France play Argentina.
"We have spoken to Sylvain about it and he has made his calculations. That Sylvain will have recovered in six months, I have no doubt. But what state will he be in?"