Matt Giteau, Toulon's instrumental back, could give the side a huge boost if he returns for this weekend's Champions Cup quarter-final.
A groin injury has sidelined the former Australia star for much of the current campaign, although he has trained fully ahead of facing Wasps.
"Matt is perhaps not able to play 80 minutes. He may therefore come on for the last 30 minutes," Bernard Laporte told the EPCR website.
Should that be the case then one of Frédéric Michalak or Juan Martín Hernández will start at fly-half.
Juan Smith and Bakkies Botha are expected to return in the pack but doubts remain about the availability of Leigh Halfpenny following his concussion in the Six Nations.