Castres - Castres scrumhalf Rory Kockott has been ruled out of Saturday's crucial Top 14 game with Oyonnax after suffering a quadriceps injury in France's Six Nations defeat against Ireland, the club's scrum coach and recently appointed consultant Maurico Reggiardo announced on Tuesday.
The 28-year-old South Africa-born player -- who became eligible to play for the French last year -- may not be fit enough either to be named in the Six Nations squad for the game with Wales on Saturday week.
However, his selection for the squad was already up in the air as his performance in the 18-11 defeat by Ireland had been criticised by coach Philippe Saint-Andre.
Reggiardo, who was brought in earlier this month to replace scrum coach Serge Milhas and also given responsibility to implement measures that will save the club's elite status, said Kockott's quadriceps injury shouldn't keep him out for long.
"He's suffering from a small injury, he'll be back for Lyon (March 7)," said 45-year-old Reggiardo, who helped save Castres top flight status back in 2007.
Castres will also have to do without inspirational Scotland lock Richie Gray, who will be missing for the rest of the season having damaged a tendon in his upper arm during Scotland's 26-23 loss to Wales on Sunday.
However, France fly-half Remi Tales and centre Remi Lamerat should start in a game that could prove pivotal to the 2013 champions hopes of staying up.
Castres are presently bottom of the table after 17 games and three points off safety with nine matches remaining.