Top 14 leaders Toulon responded brilliantly to their humiliating 41-0 defeat by Bordeaux-Begles last weekend by thrashing high-flying Montpellier 51-6 on Saturday.
Toulon scored five tries, with Jonny Wilkinson contributing 26 points, to take an 11-point lead over Toulouse, who lost to Perpignan on Friday in what was their manager Guy Noves's 1,000th match with the club.
Clermont also trail by 11 points but they can reduce it later when they host bottom side Mont-de-Marsan.
For Montpellier it was a dramatic end to a four-match winning run, and they could lose their fourth spot later should Castres beat Biarritz.
Toulon head coach Bernard Laporte said the players had responded in the perfect manner.
"This victory belongs to the players," said the former France coach.
"I am proud of how they have reacted, they have put in a great performance. They have regained their respect."
His Montpellier counterpart Fabien Galthie, who captained France under Laporte, said that they had held out some hope going into the second-half.
"We said that we could still come back in the second-half, if we got off to a good start. But sadly we conceded points early on like we did in the first-half," said Galthie.
Toulon had taken advantage early in the match of two Montpellier yellow cards, Yoann Audrin shortly followed by outstanding backrow forward Mamuka Gorgodze.
Already 6-0 up they ran in two tries, firstly through former Springbok Joe Van Niekerk, who rounded off a 60 metres move, then Nick Kennedy, who finished off a break started by Matt Giteau.
Leading 29-6 at the break, Toulon did not ease up with the sixth of Wilkinson's penalties and then the bonus point try by Benjamin Lapeyre in the 54th minute giving them an unassailable 39-6 advantage.
Giteau and then 18-year-old Ivan Roux added further tries to round off their impressive day's work.
On Friday, Perpignan's South African centre Gavin Hume scored the only try in the 19-18 win over Toulouse to shatter Noves' dream of celebrating his 1,000th match with the French champions with victory.
Hume scored with 10 minutes left with Welsh fly-half James Hook kicking the crucial extras as Perpignan came back from 18-12 down to condemn Toulouse to a first loss at their Stade Ernest-Wallon home in almost three years.
"It's a bitter defeat because I feel we dominated the match until the last 10 minutes," said Noves, who insisted he would trade the 1,000-match mark for a win.
"I'd prefer to have 100 fewer matches and have won tonight."
Noves has been associated with Toulouse since 1975 when he made his debut as a player before progressing to coach and manager.
The 59-year-old, who has led the club to a record four European Cups and been involved in 10 national titles, even turned down the opportunity to take the reins of the French national team in 2011 to remain loyal to his long-time employers.
After his 259-game playing career ended in 1988, he had overseen 740 matches as coach and manager -- including 540 in the Top 14 and a record 131 in the European Cup -- up until Friday.