Perpignan's international centre Maxime Mermoz is set to miss his side's final two Heineken Cup Pool matches after damaging his shoulder against Brive last weekend.
The French champions travel to Northampton in round five for a game that could see them return to the race for a place in the Amlin Challenge Cup quarter-finals.
Having only picked up six points from their first four Pool games, Perpignan are struggling to reach the latter stages of the Heineken Cup, but 10 points from their last two fixtures could see them finish second and potentially qualify as one of the three runners-up who cross over into the Amlin tournament.
But they will have to push for the points without their five times capped centre, who could now well struggle to make the opening game of France's RBS 6 Nations campaign.
Mermoz went to hospital after the defeat by Brive and is expected to be out of action for a month.
Perpignan complete their Heineken Cup campaign with a home clash against Benetton Treviso - who beat them in round one.
Finals Edition: Listen to the best guide to the European Rugby Cup Finals weekend in Dublin, which sees Leinster Rugby take on Stade Francais Paris at the RDS on Friday night in the Amlin Challenge Cup Final and then ASM Clermont Auvergne tackle Toulon in an all-French affair at the Aviva Stadium on Saturday.