La Rochelle pushed their lead out to 14 points in the Top 14 with a 16-5 victory over Bordeaux Begles.
A packed Stade Marcel Deflandre was a sea of yellow as the home crowd celebrated a 16th win of the season guided once again by the boot of veteran Wallaby Brock James.
James, who won the competition with Clermont back in 2010, kicked three second-half penalties to ensure victory after a tight first half.
It took a half hour for the game to spring to life, with the Bordeaux defence rushing the La Rochelle attack on their 22, James put in a delightful kick through which Kini Murimurivalu ran onto to touch down under pressure from Yann Lesgourgues and Nans Ducuing.
But just before the break Bordeaux hit back when Nans Ducuing made a break before putting Jayden Spence through. Hugh Chalmers was yellow after the restart as James added three penalties to secure victory.
Clermont Auvergne lost at the Stade Marcel-Michelin for only the second time this season as Brive kept their slim hopes of a playoff spot alive in a 26-21 win.
Brive dominated possession and inside two minutes saw Petrus Hauman charge through Judicael Cancoriet for the opening try.
After a Patricio Fernandez penalty for Clermont the yellow submarine saw Scott Spedding cross in the left corner as Thomas Domingo charged through two tackles before offloading for the French fullback to score.
But Brive roared back and fly-half Matthieu Ugalde's delayed pass to the onrushing Benjamin Petre. With Benson Stanley having anticipated a pass out wide, he rushed up, and Petre found space between Cancoriet and Stanley and crossed the line despite the best efforts of the covering Ludovic Radosavljevic.
Thomas Laranjeira converted for Brive but penalties from Fernandez and Radosavljevic, either side of a sin-binning to Laranjeira, saw Clermont lead 14-12 at half-time.
Brive pulled away in the second half as scrum-half Jean-Baptiste Pejoine sniped from a ruck on halfway. His pass to Benito Masilevu on the 10 metre line saw Matthieu Ugalde run in to score for 14 men Brive.
Still with Laranjeira in the bin, Brive pushed home their advantage with Benjamin Lapeyre gathering on his own 10 metre line. He chased his own kick and with no one at home, he collected five metres out and touched down. Morgan Parra touched down with three minutes remaining but couldn't prevent the defeat.
Leigh Halfpenny kicked 15 points as Toulon defeated Toulouse 33-23 to keep their playoff hopes alive.
Toulouse suffered a double blow early on as Maxime Medard was sin-binned, and Toulon awarded a penalty try 11 minutes in.
It got worse for the four-time European Cup winners when French captain Guilhem Guirado crossed 24 minutes in before Toulouse finally struck back through a Paul Perez try.
Halfpenny traded penalties with Luke McAlister before and with Samuel Marques after halftime as Toulon held a 23-16 lead going into the final quarter.
Then Toulon started to pull away with a drop goal from Francois Trinh-Duc and a converted Ma'a Nonu try sealing the victory. Census Johnston managed a consolation try at the death as Toulouse dropped to third from bottom in the table and Toulon are up to fourth.
Racing 92 continued their late push for a playoff spot with a 34-32 victory over Pau on Sunday.
The points from the kicking tee made the difference as Dam Carter, whose form has been criticised this term, kicked 14 points, including all four conversion, while Pau could only manage two out of five conversions.
In truth the game should have been over at half-time as tries from Joe Rokocoko, Juan Imhoff and Ben Tameifuna helped Racing to a 27-3 lead inside the half hour.
Quentin Lespiaucq grabbed a try back for the visitors but the game looked dead and buried 12 minutes after the restart when Carter converted a Henry Chavancy try to lift the Parisiens to a 32-8 lead.
In the final quarter Taniela Moa, Watisoni Votu, Romain Buros and Daniel Ramsay all crossed for Pau but with two out of the four tries going unconverted, they fell just short of victory.
Elsewhere in the Top 14 Stade Francais overcame Bayonne 32-16, Lyon edged out Castres Olympique and Montpellier defeated Grenoble.