Francois Trinh-Duc suffered what looked like a serious leg injury in his club Montpellier's Top 14 match with Oyonnax this afternoon.
The French fly-half will now be a major doubt for the November test matches against Fiji, Australia and Argentina.
Trinh-Duc, 27, who collided with Oyonnax centre Hansell Pune on 24 minutes, was hoping for a recall into the national side after missing out on the tour of Australia in June.
He has played 49 times for France since making his international debut in 2008.
