Paris - Racing 92 went top in France on superstar Dan Carter's 33rd birthday with a 38-13 win over Agen on Saturday as Toulouse again dropped points after a second successive last-gasp conversion blunder.
Racing ran in five tries for the bonus point as they put behind them a shock 13-9 loss to Castres last week.
Carter kicked 11 points but had a mixed day as the All Blacks legend lost the ball in the 23rd minute, an error which allowed George Tilsley to grab a try.
Bernard Le Roux, Virgile Lacombe (twice), Joe Rokocoko (58) and Juandre Kruger all crossed for Racing who had only led 17-10 at the interval against a team battling relegation.
Agen didn't help themselves with their own indiscipline with four players yellow-carded.
European champions Toulon, who are third, can still reclaim top spot if they win at La Rochelle on Sunday.
Replacement Jean-Baptiste Pejoine charged down a last-gasp Sebastien Bezy conversion from under the posts to earn Brive a draw in a 21-21 stalemate with Toulouse.
It was the second week running Toulouse had missed a crucial conversion with the last kick of the match as Jean-Marc Doussain's failure cost them a draw in a 31-29 defeat at home to Montpellier.
"I don't know if it's better to laugh," said Toulouse coach Ugo Mola.
"Last week, you could say (Doussain) rushed it. The angle was tight for a left-footer.
"But here, it could not have been more in front of the posts."
New Zealand international flyhalf Luke McAlister's last-minute try after late Toulouse pressure against 14 men looked set to earn a crucial victory for the visitors, with a simple conversion to follow.
But Bezy placed the ball too close to the posts, allowing an alert Pejoine the chance to dart forward and leap into the air to palm the ball down one-handed.
"It was up to me to take it back a bit to try to get it over (the charging defenders)," admitted Bezy.
"When you get that close, everyone's disappointed."
It was a comical and surreal finish to a tight match that appeared to be in Brive's pocket 10 minutes from time until Australian Alfie Mafi's sin-binning.
Bezy was off the field at that point having also seen yellow, but returned to the fray to play a pivotal role in failing to give his side victory.
Brive led 8-6 at half-time thanks to the only try of the opening period as hooker Francois Da Ros burrowed to within inches of the line before scrum-half Teddy Iribaren swung the ball left for South African lock Johan Snyman to flop over.
Toulouse went back in front 10 minutes into the second half as Maxime Medard zig-zagged through the Brive defence from close range. but Fijian wing Sevenaia Galala did brilliantly to gather and ground an Iribaren grubber kick on the dive to restore the home side's advantage.
With just over 10 minutes left, Toulouse were two scores behind but Mafi's yellow card gave Doussain the chance to kick Toulouse back to within a score.
There was still time for McAlister to go over and set up a winning kick for Bezy, but scrum-half Pejoine had other ideas.
Bordeaux-Begles maintained their hold on fourth place as Australia back Adam Ashley-Cooper scored a hat-trick in a 48-20 victory over rock-bottom Oyonnax.
Champions Stade Francais's miserable season continued as they dropped to third-from-bottom with a 19-12 defeat at Pau.
On Friday night, France wing Noa Nakaitaci scored a hat-trick as Clermont briefly went top with a 45-12 win at Grenoble.
It was a third straight win for Franck Azema's team, for whom former England wing David Strettle, Wales centre Jonathan Davies and replacement scrum-half Enzo Sanga also scored, while Morgan Parra went six from six with the boot.
Grenoble dominated in terms of possession and territory but were punished three times for turnovers in the first period as Clermont clinically scored five tries before the break.