Toulon loose forward and Argentina captain Juan Martin Fernandez-Lobbe has been sidelined for six weeks with a ruptured spleen.
The 31-year-old suffered the injury in the Top 14 leaders' 51-6 victory over Montpellier last weekend.
Fernandez-Lobbe came off in the 44th minute after a tackle left him with minor internal haemorrhaging.
Toulon have confirmed on Tuesday that he is still undergoing treatment in hospital, but he does not require surgery.
The former Sale back-row will miss the Top 14 clash at Castres on February 22 with a return to action expected on April 14 when Toulon play Clermont.