Morgan Parra's late try finally put an end to Toulon's stubborn resistance as Clermont went top of the Top 14 with a 22-19 win.
Toulon had put out a weakened side, choosing to rest some of the best players for the knockout stages with young Australian fly-half UJ Seuteni making his first appearance for the club.
It didn't seem to bother them though, and it was Toulon who dominated the opening exchanges, and probably should have made more of a number of early chances.
Clermont weren't helped by the loss of both Ludovic Radosavljevic and Camille Lopez to injury in the first half-hour, with the latter's adductor problem particularly concerning two days before the announcement of France's preliminary World Cup squad.
Parra and Mike Delany replaced them, with Parra also getting a knock early and having to play through the pain however he was able to carry on and make the difference in the last ten minutes.
Delany's kicking ended up being vital for les Jaunards, who never really seemed to settle into the game, and Josua Tuisova's try in the closing stages earned an important bonus point for the visitors.
Having lost to Toulon two weeks ago in the Champions Cup final, Clermont again looked fragile and did little to convince that they can win if the two meet again in the Top 14 play-offs.
Toulon opened up a 6-0 lead thanks to two Eric Escande penalties, although Seuteni had a try disallowed for a forward pass by Tuisova.
Things got worse for Clermont when Benson Stanley was sin-binned for a tackle without the ball on Bryan Habana, playing out of position at full-back.
However the loss of the former All Black centre didn't seem to affect the home side, with Delany knocking over two penalties to make it 6-6 at the break.
Clermont started the second half on the front foot, and when Toulon were penalised for slowing the ball down in a ruck Delany gave the home side the lead for the first time.
The game was being played almost exclusively in the Toulon half, and while Clermont were struggling to break through, the visitors were regularly penalised for illegally slowing the ball, with Delany making it 12-6 after 50 minutes.
Toulon responded though with a third penalty from Escande after Sébastien Vahaamahina had been caught offside.
The visitors were soon down to 14 though, with skipper Gerhard Vosloo sin-binned against his former team. The flanker caught Delany with a stray boot in a ruck, although it seemed a very harsh decision from what seemed to be an accident. After being patched up Delany knocked over three more points for the hosts.
Much like Clermont, being a man down didn't seem to affect Toulon, and when Benjamin Kayser was penalised just after the hour, it allowed the visitors to get back into Clermont territory and earn three more points from Escande.
Clermont looked nervous, but with ten minutes to go they scored the first try of the game thanks to a quick tap from Parra. The scrum-half spotted Toulon a little slow to retreat and was able to force his way over, with Delany converting from out wide.
With five minutes remaining Kayser put in a tackle off the ball on Levan Chilachava, and after taking the scrum Toulon spread the ball wide for Tuisova to score on the right, with replacement Anthony Méric converting from the touchline.
Clermont should have had a try with the final play of the game however when Parra went over again, but Pascal Pechambert, in his final game as a referee oddly considered Parra stretching for the line as a double movement.
It was a crucial decision, as it leaves Toulon top of the table going into the final round of matches, with Clermont, Stade Français and even Toulouse still in with a chance of a place in the top two and an automatic semi-final spot.
Pens: Delany 5
Yellow Card: Stanley
Pens: Escande 4
Yellow Card: Vosloo
Clermont: 15 Nick Abendanon, 14 Wesley Fofana, 13 Benson Stanley, 12 Jonathan Davies, 11 Noa Nakaitaci, 10 Camille Lopez, 9 Ludovic Radosavljevic, 8 Fritz Lee, 7 Julien Bardy, 6 Damien Chouly (c), 5 Sébastien Vahaamahina, 4 Paul Jedrasiak, 3 Davit Zirakashvili, 2 John Ulugia, 1 Thomas Domingo
Replacements: 16 Benjamin Kayser, 17 Vincent Debaty, 18 Julien Pierre, 19 Julien Bonnaire, 20 Morgan Parra, 21 Mike Delany, 22 Napolioni Nalaga, 23 Clément Ric
Toulon: 15 Bryan Habana, 14 Josua Tuisova, 13 Jimmy Yobo, 12 Maxime Mermoz, 11 David Smith, 10 UJ Seuteni, 9 Eric Escande, 8 Virgile Bruni, 7 Mamuka Gorgodze, 6 Gerhard Vosloo, 5 Jocelino Suta, 4 Romain Taofifenua, 3 Martin Castrogiovanni, 2 Craig Burden, 1 Florian Fresia
Replacements: 16 Jean-Charles Orioli, 17 Alexandre Menini, 18 Konstantin Mikautadze, 19 Stephane Muñoz, 20 Anthony Belleau, 21 Théo Bélan, 22 Anthony Méric, 23 Levan Chilachava
Venue: Stade Marcel Michelin, Clermont-Ferrand
Referee: Pascal Pechambert