Paris - Montpellier's South African coach Jake White has vowed to fight for second place when his team travel to Racing 92 on Sunday.
The European Challenge Cup winners face a three-way battle to join Clermont in a top-two finish and a bye into the end-of-season play-off semi-finals.
Montpellier have on paper the toughest task as they travel to European Cup finalists Racing, while Toulon are at home to Bordeaux-Begles.
Racing and Toulon trail Montpellier by four points ahead of Sunday's final round of regular season matches.
There had been talk of Montpellier putting out a virtual second-string side to allow their first choice players to rest up for a week before the post-season play-offs begin, but White dismissed such a possibility.
"We started preparing for this season 11 months ago, so in any case, everyone's tired. It's tough for all the teams," said White, who led South Africa to World Cup glory in France in 2007.
"We have an opportunity, it would be crazy to not try to take it."
The permutations for who will take second place remain complicated but if Montpellier avoid defeat in Paris they will guarantee a second-placed finish.
In the case of a defeat, bonus points -- either attacking or defensive -- will come into play.
Montpellier, Toulon and Racing could even finish on equal points at the season's end, meaning head-to-head records will decide who finishes second.
Currently, Toulon have the edge over Montpellier, who would have the better head to head with Racing should the two finish level on points.
Should Racing and Toulon end on the same points, it would be the Parisians who finished above.
All of which means that until the matches finish, it will unlikely be clear who is set to finish second.
Montpellier do at least know that a win or draw will definitely be enough for them, and they could even take top spot with a victory if Clermont suffered a shock loss at home to La Rochelle.
The other major element to be decided is who takes the sixth and final place in the play-offs.
Castres and Bordeaux are level on points but the latter have the head-to-head advantage.
They also have much the easier match on Sunday, hosting reigning champions Stade Francais, who must be desperate for their miserable season to end.
Stade will almost certainly finish third from bottom after a dismal defence of the title they won in beating Clermont in last year's final.
Castres know that a win will leave them in a strong position as Bordeaux, for whom New Zealander No.8 and captain Matthew Clarkin is likely to play his final match, face a daunting trip to Toulon.
The three-time European champions had expected to welcome back Wales full-back Leigh Halfpenny for the match but the British and Irish Lions star broke down with a muscular problem during training on Tuesday and will be rested for another two weeks.
The teams finishing third and fourth will host those ending up fifth and sixth in the play-off quarter-finals next weekend.
Fifth-placed Toulouse could book a home semi-final if they win at Grenoble and either Racing or Toulon lose.