France scrum-half Antoine Dupont starred as Toulouse eased past Toulon 51-27 in the French Top 14 on Saturday as Montauban were relegated after a 59-7 hammering at Montpellier.
Dupont scored one of the holders' six tries and provided two assists in a game held in Marseille to send them 12 points clear of second-placed Montpellier at the summit of the table.
Dupont's side are on the verge of claiming an automatic semifinal berth with just three rounds of the regular season to play having suffered a surprise defeat at home to Clermont in their previous Top 14 outing.
"Considering our last league game we wanted to show another side of ourselves," Dupont told Canal+.
"It wasn't easy, but it paid off in the end, it's for us to switch our mentality for the end of the season now," the 29-year-old added.
Defeat left Toulon, who were knocked out of the Champions Cup semifinals last Saturday by Leinster, facing a challenge of reaching the play-offs, trailing Bordeaux-Begles in sixth by nine points.
Toulon led 20-17 after 38 minutes with full-back Melvyn Jaminet slotting a penalty goal from 60m despite rain at the home of Marseille's football club.
However, Dupont crossed just before the break, which sparked victory for Toulouse, who broke the Top 14's regular season record haul during the match.
Earlier, Argentina centre Justo Piccardo scored four tries to send Montauban and their meagre financial budget down to ProD2 after just one season, when they managed just one win and a draw by conceding a record number of a tries and points in one Top 14 campaign.
"We were ready for relegation. Now it's official but that doesn't change much about the end of our journey," Montauban head coach Sebastien Tillous-Borde told reporters.
"We've already worked on a lot of things for next season," the former France scrum-half added.
Montpellier crossed for nine touchdowns in total as they moved to second place by leapfrogging Pau, who had beaten Castres 27-15 earlier in the day thanks to 11 points from English fly-half Joe Simmonds.
Tillous-Borde's side had to beat Montpellier to keep any hope of overlapping Perpignan in 13rd place, the relegation play-off berth.
That aspiration was all but over by halftime on the Mediterranean coast as Montpellier led 26-0, thanks to Piccardo crossing three times in 33 minutes.
The only consolation for 1967 French champions Montauban was a try for 19-year-old Fijian winger Asaeli Gade as Montpellier added five efforts after the break, including 24-year-old Piccardo's fourth.
Elsewhere, fellow strugglers Perpignan will face the loser of the ProD2 promotion final in a relegation play-off after also suffering a heavy defeat, losing 45-14 at Clermont.
Former New Zealand fly-half Harry Plummer scored 20 points for Les Jaunards, who strengthened their grip on a play-off spot.
Scrum-half Maxime Lucu slotted a 76th minute conversion as last season's runners up Bordeaux-Begles edged Bayonne 40-38 a week on from reaching the Champions Cup final.
Lucu's side are four points below Stade Francais in fourth after the Parisians thumped Lyon 59-17.
On Sunday, Racing 92 host Ronan O'Gara's La Rochelle with both sides still holding a mathematical chance of reaching the top six.