All Black legend Dan Carter is expected to return from a turbulent six-week lay-off as reigning French champions Racing 92 host surprise Top 14 leaders La Rochelle this weekend.
The 35-year-old has not played since the end of January due to a groin injury and last month issued a grovelling apology after he was caught drink-driving in Paris.
But Racing hope the two-time world champion can serve as the springboard for the misfiring champions to revive their hopes of a top-six finish and a place in the play-offs.
The Paris club are seventh at present, a point behind Toulon, and could also welcome back Casey Laulala on Saturday alongside Henry Chavancy at centre after two months out.
La Rochelle stunned struggling heavyweights Toulouse last weekend to climb above Clermont at the summit and tied down New Zealand forward Jason Eaton, the club captain, for a further season on Wednesday.
They will be without forwards Uini Atonio and Kevin Gourdon, both on France duty against Italy in the Six Nations, while Racing pair Brice Dulin and Bernard Le Roux are also in Rome.
Camille Lopez, Remi Lamerat, Noa Nakaitaci and Paul Jedrasiak will be missing for title hopefuls Clermont at home to fourth-placed Montpellier on Sunday.
The hosts lost 26-16 at Castres last time out but are a formidable force at the Stade Marcel-Michelin, where they are a perfect nine from nine this season.
While Montpellier remain on course for the play-offs, wing Benjamin Fall acknowledged they must pick up points on their travels to avoid falling out of contention.
"It could be a decisive match for the rest of the season," Fall said. "More generally, this month of March is crucial. We're on the road twice in the next three matches. We need to be able to pick up wins away from home to stay in the top six.
"We let an opportunity pass us by at Lyon, but there are still several more chances.
"As far as the top two (and a play-off bye), I think La Rochelle and Clermont have such a lead that it will be difficult to catch them."
- Unwanted history -
Three straight defeats have left Toulouse in serious jeopardy of missing the play-offs for the first time in 41 years, with the record 19-time champions toiling in eighth place.
"I don't think the club has found itself in this type of situation for a really long time," said coach Ugo Mola, whose side have lost 10 times in 19 outings this term.
"Right now we're going through a tough time but there are seven matches left and to surrender is not how things are done here."
France coach Guy Noves, Toulouse's long-serving former boss, has selected Gael Fickou, Cyril Baille and Yoann Maestri in his XV to play at the Stadio Olimpico on Saturday, while Richie Gray will be in action for Scotland away to England.
Sixth-placed Toulon will fancy their chances of rolling over rock-bottom Bayonne at home, while Castres visit Pau in a potential dress rehearsal for the end-of-season play-offs.
Fixtures (all times GMT)
Bordeaux-Begles v Grenoble, Lyon v Stade Francais, Toulon v Bayonne (1730), Brive v Toulouse (1800), Racing 92 v La Rochelle (2000)
Pau v Castres (1130), Clermont v Montpellier (1600)