Biarritz ran three second-half tries past Montpellier at Parc des Sports d'Aguilera on Saturday to win 27-8 and continue their unbeaten start to the Top 14 season.
The Basques started the weekend level at the top of the starting with Toulon having won all three of the previous fixtures.
It was all square at 3-3 at half time but two yellows cards within the space of four minutes put paid to Montpellier's chances as the hosts used their numerical advantage to score three tries in the last 25 minutes.
A 79th-minute try from Montpellier centre Thomas Combezou - who had returned from the sin bin - denied Biarritz a bonus point however.
Biarritz pivot Jean-Pascal Barraque opened the scoring in the 20th minute, slotting over a penalty after having missed two earlier opportunities and, surprisingly having been all but inch perfect so far this season, he was to miss two further opportunities later in the first-half.
That allowed the visitors to not only stay in the game but even went in on level terms as France fly-half Francois Trinh-Duc dropped a goal four minutes from half-time.
The unfortunate Barraque was replaced seven minutes into the second-half by Julien Peyrelongue, who quickly slotted the hosts into a 6-3 lead.
They were to extend it in the 55th minute profiting immediately from the sin-binning of Montpellier's Fijian star Timoci Nagusa as the outstanding former England full-back Iain Balshaw went over after being slipped the decisive pass by American flyer Takudzwa Ngwenya.
Peyrelongue converted for 13-3 and Montpellier's task became mission impossible when they were further reduced as centre Thomas Combezou was also yellow-carded.
Biarritz extended their lead when they ran in a second try by Benoit Guyot, which was also converted by Peyrelongue, and added a third in the 67th minute through a brilliant individual effort by 21-year-old scrum-half Yann Legourgues - Peyrelongue adding the two points.
Combezou redeemed himself slightly when he touched down for a late consolation try for the visitors.
Tries: Balshaw, Guyot, Lesgourgues
Cons: Peyrelongue 2
Pens: Barraque, Peyrelongue
Yellow cards: Nagusa (Montpellier - 54th min - foul play); Combezou ( Montpellier - 58th min - late tackle)
Biarritz: 15 Iain Balshaw , 14 Takudzwa Ngwenya , 13 Charles Gimenez, 12 Damien Traille, 11 Aled Brew, 10 Jean pascal Barraque, 9 Yann Lesgourgues , 8 Raphael Lakafia, 7 Wenceslas Lauret, 6 Magnus Lund, 5 Erik Lund, 4 Jerome Thion, 3 Eugene Van staden, 2 Arnaud Heguy, 1 Wikus Blaauw.
Replacements: 16 Benoit August, 17 Fabien Barcella, 18 Pelu ian Taele, 19 Benoit Guyot , 20 Julien Peyrelongue, 21 Benoit Baby, 22 Seremaia nakala Burotu, 23 Benedict Broster.
Montpellier: 15 Jean baptiste Peyras, 14 Timoci Nagusa, 13 Thomas Combezou, 12 Paul Bosch, 11 Yoan Audrin, 10 Francois Trinh-Duc, 9 Julien Tomas, 8 Alex Tulou, 7 Alexandre Bias, 6 Fulgence Ouedraogo, 5 Mamuka Gorgodze, 4 Thibaut Privat, 3 Vincent Pelo, 2 Michael Ladhuie, 1 Yvan Watremez.
Replacements: 16 Fabien Dorey, 17 Mikheil Nariashvili, 18 Hendrikus Hancke, 19 Kevin Gimeno, 20 Benoit Paillaugue, 21 Pierre Berard, 22 Yohann Artru, 23 Erasmus Jansen van Vuuren.
Referee: CÚdric Marchat