Montpellier scrum-half Julien Tomas will miss Saturday's Heineken Cup quarter-final against compatriots Clermont.
Tomas is still recuperating from being knocked out playing Mont-de-Marsan in last weekend's Top 14 clash.
He had tests at the start of the week but was unable to train on either Tuesday or Wednesday as the squad held sessions at nearby Agde.
Tomas had to go off midway through the first-half after he collided with second-rower Wame Lewaravu, giving way to Benoît Paillaugue.
Eric Escande has been drafted into the squad in his place.
Argentinian international centre Santiago Fernandez is set to play having recovered from a toe fracture suffered against Bordeaux-Bègles on February 23.