Toulouse reclaimed top spot in France after maintaining their unbeaten home record at the weekend by beating European champions Toulon 13-12.
The blustery conditions in Toulouse even got the better of former England flyhalf Jonny Wilkinson who missed three chances in the final 10 minutes, including a drop goal attempt on the buzzer.
Toulouse lead Clermont, who defeated Brive 36-29, by two points with Toulon and Montpellier, surprisingly beaten 24-19 by struggling Bayonne on Friday, both a point further back.
Stade Francais squandered a chance to go second when they lost 16-12 to local rivals Racing-Metro.
Toulouse, playing into a strong wind, had a wretched opening period, losing influential No.8 Louis Picamoles in the 10th minute with what appeared to be a similar hip injury to the one the 27-year-old suffered on the close season France tour of New Zealand.
Scans will determine whether the 38-times capped star will be able to join up with the national squad ahead of the November tests.
Former Toulouse star Frederic Michalak opened the scoring for Toulon with a penalty, the home fans booing him, as Toulon tried to rebound from their surprise defeat in the European Cup last weekend to Cardiff.
Michalak, who only returned to match action last weekend after a long absence because of a shoulder injury, doubled the visitors' lead in the 19th minute with another penalty from long range.
He added another two by the half hour mark for a 12-0 lead, the latter after Jean-Pascal Barraque was sin-binned and though the hosts got another chance at a penalty his replacement as kicker, South African scrum-half Jano Vermaak, missed with a penalty in front of the posts.
Barraque finally put Toulouse on the board soon after the restart, but his errant ways returned a few minutes later as he missed from in front of the posts.
Toulon suffered a serious blow when veteran Argentinian lock Juan Fernandez Lobbe had to be taken off 15 minutes after coming on with what was later diagnosed as a broken right elbow.
Wilkinson was sent on on the hour mark, replacing Michalak, while Toulouse manager Guy Noves sent on Jean-Marc Doussain to see if he could add something to their kicking game, but he too failed with his first attempt at goal from over 40 metres out.
However, Toulouse finally moved ahead 10 minutes from time as Vermaak went over for a try and Doussain converted.
Toulon had two chances to regain the lead but even Wilkinson could not get the ball over between the posts, first from wide out on the left and then from a more kickable position.
Wilkinson had one final chance to steal the points but his drop goal drifted wide of the posts to give Toulouse a deserved win.
Toulon captain Sebastien Tillous-Borde blamed a poor second-half display for their defeat.
"In the second-half we made too many errors, we lacked discipline but in spite of that we still had chances to win but I am still pleased with the spirit of the team," he said.
"We will just have to work harder."
His Toulouse counterpart Thierry Dusautoir said that the toughness of the match will have served them well.
"Being 12-0 down to Toulon is complicated but in the second-half we managed to be more effective with the ball," said the flanker.
"It's not too bad to have stressful matches like this when you win them."
Racing Métro 92 16-12 Stade Français
Castres Olympique 39-0 Biarritz Olympique
ASM Clermont 36-29 CA Brive-Corrèze
Grenoble 23-10 Oyonnax
Perpignan 31-20 Union Bordeaux-Bègles
Stade Toulousain 13-12 Rugby Club Toulonnais
Aviron Bayonnais 24-19 Montpellier Hérault Rugby