Biarritz top the standings after a 22-17 triumph over defending champions Toulouse at their Parc des Sports d'Aguilera home.
Veteran centre Damien Traille scored Biarritz's sole try, with fly-half Jean-Pascal Barraque adding the remainder of the points with the boot.
Vicent Clerc saved a bonus point for Toulouse with a late try.
Former England international flanker Steffon Armitage - who this summer was briefly suspended for a positive morphine test most likely caused by medication prescribed by the club for back pain - crossed for Toulon in a closely-contested first half at Mont-de-Marsan.
However Toulon, who led 14-12 at the break and fell briefly behind at the start of the second half, ran out 29-15 winners with further tries from back rowers Joe van Niekerk and Pierrick Gunther.
England legend Jonny Wilkinson kicked two penalties and a conversion for Toulon, while Mont-de-Marsan are yet to score a point in this season's championship.
There were 11 tries in Clermont as Perpignan lost their third consecutive game 53-31 while Agen's 32-15 defeat in Montpellier leaves them the third team to lose all three matches.
Castres beat Bayonne 31-10 at home and Racing eased past Bordeaux-Bègles 18-7 in Paris.
- Damien Traille