Toulon secured direct qualification for the Top 14 semi-finals on Sunday as Clermont Auvergne ended the regular season at the summit and Castres pipped Bordeaux-Begles to the final play-off place.
Clermont began the final round of fixtures as league leaders and ensured they could not be caught courtesy of a 57-8 thrashing of La Rochelle.
However, Toulon - comfortable 44-3 winners over Bordeaux - were able to leapfrog Montpellier into second place, as the latter went down 40-25 to Racing 92.
While Toulon can now enjoy a week off ahead of their last-four tie, Montpellier must prepare for a quarter-final against Castres, who ended their regular campaign with a 35-14 triumph over 2014-15 champions Stade Francais. The winner of that last-eight match will meet Toulon.
The other quarter-final will see Racing face Toulouse for the right to take on Clermont, while Bordeaux can at least take consolation from the fact their seventh-placed finish is enough to earn a European Champions Cup place following Montpellier's Challenge Cup victory last month.
Juan Imhoff scored two of Racing's four tries against Montpellier, who were left with too much to do after falling 14 points behind inside the opening half an hour in Colombes.
Clermont ran in nine tries against La Rochelle, David Strettle grabbing a hat-trick, while Toulon enjoyed a similarly comfortable evening following the first-half dismissal of Bordeaux's Metuisela Talebula.
Castres' victory over Stade was inspired by Rory Kockott, who crossed twice en route to a 25-point individual haul.
The departing Clement Poitrenaud opened the scoring as Toulouse romped past Grenoble 53-14, while Brive beat Pau 46-10 and Agen edged to a 23-19 win over Oyonnax despite being reduced to 14 men early on.