Defeats for the top two have thrown the race for Top 14 semi-final spots wide open on Friday, with five teams now jostling for the top spot.
Castres and Clermont both tumbled away from home, 19-6 to Toulon and 22-13 to Bayonne respectively, while chasers Toulouse and Perpignan won 34-3 and 19-14 at home to Montpellier and Biarritz respectively.
Stade Français' season lurched from bad to worse with a 26-14 defeat at Brive, while Bourgoin lifted themselves further away from relegation with a 17-7 win at Albi.
Friday, March 12
Toulon 19-6 Castres
Bayonne 22-13 Clermont
Toulouse 34-3 Montpellier
Albi 7-17 Bourgoin
Brive 26-14 Stade Français
Perpignan 19-14 Biarritz
Saturday, March 13
1 Castres 67
2 Perpignan 66
3 Clermont 65
4 Toulouse 65
5 Toulon 63
6 Racing Metro 55
7 Brive 51
8 Stade Français 49
9 Biarritz 48
10 Bourgoin 44
11 Bayonne 43
12 Montpellier 42
13 Montauban 41
14 Albi 19
RC Toulon 19-6 Castres Olympique
As is often the case in France, the match was pretty much decided by a first half in which the home side, unbeaten at the fortress Felix Mayol this season, put in a display of searing intensity.
Mafi Kefu's try bolstered three penalties from Felipe Contepomi, while a single solitary penalty from the boot of Cameron McIntyre was all Castres could muster - even that was with the final kick of the half.
Castres have spent much of this season blowing away better teams with their own intensity so it was about time someone took them on at their own game.
But it was the Contepomi-Sonny Bill Williams combination that created the difference. It worked for the first try and it did for the second as well, with flanker Olivier Missoup looping round to finish off. That made it 19-3, and a McIntyre penalty was again all Castres could find in response.
Aviron Bayonnais 22-13 Clermont Auvergne
A chance for Clermont to go top was badly missed here as Bayonne further hauled themselves away from relegation.
Centre Sam Gerber crossed for a Bayonne try in the second minute as the home side roared out of the blocks and Cedric Garcia added to it with two drop goals and the conversion, while Seremaia Bai at least got Clermont on the board in an opening quarter-hour dominated by the hosts.
Bai pulled a penalty back just before the break, but that was it for the scoring until the hour mark, when Garcia made it 16-6 with his first penalty.
Ten minutes before time though Clermont struck back with a try for Anthony Floch and conversion by Brock James.
But Garcia extended the lead with his second penalty and his third, in the final minute and as a result of the disciplinary nightmare that is Jamie Cudmore - he had been yellow-carded in the first half - denied Clermont even a bonus point.
Stade Toulousain 34-3 Montpellier HRC
Five tries to nil for Toulouse, who look to be hitting form at the right time of the season.
All five came in the first half, one which even understated - when it comes to compliments anyway - coach Guy Noves called an 'exceptional' half of rugby.
Yann David, Virgil Lacombe, Jean Bouilhou, Cedric Heymans and Vincent Clerc all touched down in the same 20-minute spell, with David Skrela adding three conversions to his earlier penalty for a 34-0 half-time lead.
Montpellier, shell-shocked, at least spared themselves the ignominy of a nilling with a penalty from Cesar Sempere early in the second half, but that was pretty much it as far as the game went, with Toulouse in cruise mode.
SCA Albi 7-17 CS Bourgoin-Jallieu
A penalty try right on half-time gave Bourgoin the necessary momentum to survive a gruelling test of resolve in Albi, whose goose is now surely cooked as far as the top flight goes.
Alberto di Bernado's conversion, added to that of John Senio's earlier try, gave Bourgoin a 14-0 half-time lead, too much for Albi to pull back.
Pierre-Gilles Lakafia's try gave Albi some hope but when lock Thomas Vervoort was yellow-carded for a late tackle about two minutes after coming on as a replacement, hope evaporated.
CA Brive-Corrèze 26-14 Stade Français
It's a defeat which probably means the Parisians will not make the play-offs this season, but on this performance you'd never think they were even worthy of such on paper.
They trailed 19-6 at the break, with Fabrice Estebanez in deadly form with the boot and also finding time and space to set Nicolas Jeanjean up for a superb try.
Lionel Beauxis' third penalty made it 19-9 early in the second half but heavy Brive pressure resulted in first, a yellow card for Rodrigo Roncero and then, a minute later, a penalty try which killed the game off.
Hooker Laurent Sempere got a late try for the visitors but it was no consolation for a season surely now lost and for a likely lack of even a Heineken Cup spot to show for it.
USA Perpignan 19-14 Biarritz Olympique
The tries came early but the tension built and built in the Stade Aimé-Giral. Jean-Philippe Grandclaude's opening score was quickly cancelled out by one from Iain Balshaw - the latter try a gem of a score from one side of the field to the other - but Nicolas Laharrague's conversion separated the two sides after 15 minutes.
That was the trademark of a Biarritz first forty minutes where they managed everything but a score, a factor which would haunt them at the end.
Laharrague and Valentin Courrent exchanged penalties before the break and after it, sharing six in all as Perpignan just kept their noses in front despite playing for ten minutes without scrum-half Nicolas Durand, who interfered with ruck ball just as Taku Ngwenya was ready to steam home.
Perpignan held firm though and made sure of victory when Laharrague landed his fourth of the night six minutes from time - sinking a heavy nail into the coffin of Biarritz's play-off hopes.