Clermont missed the chance to jump into the top two places of the Top 14, going down 19-10 to Stade Français on Saturday.
It's a result which gives Saturday's late match winners Perpignan a clear lead at the top with only two matches to play.
Biarritz kept themselves in touch with the play-off places with a handsome 42-13 win at home to Montauban, but not nearly as handsome as Montpellier's nine-try 62-17 demolition of Albi.
Brive kept faint play-off hopes alive with a 25-15 win over Bourgoin, while Toulon sit third after a 31-13 win over Bayonne which puts the Basques back in thirteenth and guarantees Toulon at least a play-off berth.
Friday, April 2:
Toulouse 28-23 Racing Metro
Saturday, April 3:
Montpellier 62-17 Albi
Toulon 31-13 Bayonne
Brive 25-15 Bourgoin
Biarritz 42-13 Montauban
Stade Français 19-10 Clermont
Castres 11-17 Perpignan
1 Perpignan 75
2 Castres 72
3 Toulon 72
4 Clermont 70
5 Toulouse 69
6 Racing-Métro 92 60
7 Biarritz 57
8 Brive 57
9 Stade Français 53
10 Montpellier 47
11 Bourgoin 45
12 Montauban 45*
13 Bayonne 43
14 Albi 20
*Montauban will be relegated irrespective of league position because of financial irregularities
Stade Français 19-10 ASM Clermont Auvergne
All the scoring came in the first half of a match which the home side won by unashamedly using a dire kicking game that will have done nothing for the pulses of 72,000-odd souls packing the Stade de France.
Clermont scored first, working their way into the Parisian 22 where Vermeulen's drive was finished off by Domingo after five minutes, but Stade's response was quick: a tap penalty from Oelschig and a rumble to the line from Dimitri Szarzewski.
Oelschig was involved in the try that took the lead for the home side as well, making an excellent break and long pass to find Bastareaud, who popped up the ball out of an ankle-tap tackle to Mark Gasnier for the score.
Morgan Parra reduced the deficit with a penalty but Szarzewski scored his second on the stroke of half-time to put his side 19-10 ahead.
Lionel Beauxis' missed penalty was pretty much the sum total of action in the second half, with Clermont leaving the field desperately disappointed and now facing a clash against Castres that will decide whether they get a play-off place or an automatic semi-final.
Biarritz Olympique 42-13 Montauban
It's a remote possibility, but should Biarritz progress in this form and Racing Metro slip up in sixth, Biarritz could yet have rescued a season that looked to be already flushed down the pan and surging out to sea.
The Biarrots led 35-3 at half-time, courtesy of a four-try blitz in the final 15 minutes of the first half also marked by a punch-up which saw Montauban prop Benjamin Sa sent off and hookers Greg Arganese of Montauban and Eduard Coetzee sent to the bin.
Taku Ngwenya scored two, as well as one each for Damien Traille, Karmichael Hunt and Florian Faure. Dimitri Yachvili was faultless from the tee.
The second half was tamer both in spirit and scoring. Back-row Mirko Lozupone and young centre Felix Le Bourhis scored tries for Montauban and Julien Peyrelongue wrapped up the home team's scoring with a late try, once again converted by the excellent Yachvili.
Montpellier HSC 62-17 SCA Albi
Benjamin Thiery set the tone for this match when he took the ball off the blindside of the first ruck and raced all the way downfield past three defenders to score Montpellier's first.
Thierry Brana followed with a try after five minutes, then Mamuka Gorgodze after 14, then Federico Todeschini after 19... you're getting the drift.
Albi did actually get a couple of tries of their own, one in the first half to Sebastian Pages and the other in the second to Saula Radidi.
Otherwise it was all Montpellier, with Gorgodze grabbing a second, Francois Trinh-Duc also grabbing two and Sebastian Petit and Julien Alcalde rounding off the try-scoring.
Todeschini converted five of the tries - also landing a slightly out of place looking penalty - and Trinh-Duc two others
RC Toulonnais 31-13 Aviron Bayonnais
Bayonne would be in deep trouble after this defeat had it not been for Montauban's indiscretions in their budget. Toulon, on the other hand, guaranteed at least a play-off place and ought to be in the top two once Castres and Perpignan have finished.
The home side were in rampant form, running in three first-half tries through Gabriel Lovobalavu with two and Sebastian Bruno, with Jonny Wilkinson landing three penalties and a conversion for a 26-6 lead - a rueful-looking Sebastian Fauque, who left Toulon earlier in the season moaning about no first-team rugby, landing two kicks for the Bayonnais.
Dwayne Haare's try for Bayonne in the 47th minute meant Toulon no longer had the bonus point and the home side got frustrated, with Davit Kubriashvili and Tana Umaga both sent to the bin, but eventually Fabien Cibray managed to get the try that saw Toulon sit atop the table for a few hours.
CA Brive-Corrèze 25-15 CS Bourgoin-Jallieu
Three tries to nil for a surprisingly sprightly-looking Brive who have clearly not yet given up hope on the final play-off place being courted by both Biarritz and Racing Metro.
Gerhard Vosloo and Ronnie Cooke scored for Brive, with Alexis Palisson converting one and adding two penalties, but Bourgoin, as is so often the way, were kept in touch by the boot of Benjamin Boyet with three penalties and a drop goal.
Boyet landed his fourth penalty and the game was tight up to the end, but Bourgoin's pack, which had been grafting all day to keep the team in the game, finally crumbled and gave away a penalty try.
Castres Olympique 11-17 USA Perpignan
A huge coup for the champions, a little reality check for Castres, who find themselves battling with some very big names indeed for play-off places.
Castres were undefeated at home until this match, but this time of the season tends to bring out the best in people and Perpignan delivered a sterling display worthy of champions.
They took the early lead courtesy of a Farid Sid finish that owed everything to a pass from Julien Candelon that was nearly intercepted but instead fell to Henry Tuilagi, with the Samoan setting Jerome Porical - who converted the try - and then Sid away.
But Castres fought back, first through a penalty by Ro,main Teulet, then through a try by returning wing Mathieu Nicolas, who took a high wide kick from Cameron McIntyre.
Perpignan were reduced to fourteen men after a high tackle from Ovidiu Tonita, but still took the lead back with a barnstorming run from Tuilagi for his side's second score, with Porical again converting.
Teulet halved the arrears from 14-8 to 14-11 with a penalty, but when Porical missed a penalty moments later, Gavin Hume was on hand to help bolster the lead with a drop goal to make it 17-11.
That was it - Castres had run out of ideas. Perpignan's title defence looks on course while Castres now have Clermont and Toulouse to contend with on successive weekends.