This is a victory that changes everything
Springbok star Bryan Habana scored a try on his return to action after a three-month absence because of a hamstring injury as Toulon beat Bordeaux-Begles 22-20.
The 30-year-old - a World Cup winner in 2007 - touched down in the 66th minute as Toulon came from 20-9 down to prevail, largely thanks to 14 points from Frederic Michalak, and provisionally go top of the table ahead of Saturday's later matches.
They head Clermont, who beat defending champions Castres on Friday, on a better head to head record
Bordeaux - who thrashed Toulon 41-0 in the corresponding home fixture last season - moved to the sixth and final play-off spot with a defensive bonus point.
Toulon backs coach Pierre Mignoni, whose boss head coach Bernard Laporte is serving a 16-week ban, said he was delighted with the result because at one point he feared they would be 30 points down.
"This is a victory that changes everything," said the 37-year-old former French international scrumhalf, capped 28 times.
"To win the match after a catastrophic first half where we weren't in the match, I have to congratulate the players for their comeback."
Bordeaux made a scintillating start and took the lead in the second minute through a try by Samoan hooker Ole Tavei, the score stemming from a deliberate knock on by Habana.
Former Castres star Pierre Bernard converted for 7-0.
Lively Bordeaux scrumhalf Heni Adams then sparked another incisive surge into Toulon territory by Felix Le Bourhis but Toulon cleared.
However, Bordeaux didn't let up and went 10-0 up in the 24th minute through a penalty by Bernard after Habana was sin-binned for deliberately preventing the ball being played by the hosts.
Toulon got off the mark on the half hour mark as Michalak landed a penalty but Bordeaux deservedly extended their lead with another superb try in the 34th minute.
Another quick delivery by Adams saw Bernard pierce the Toulon backline and power 30 metres deep into the visitors' half, before unselfishly offloading to Le Bourhis, who had the legs on the Toulon defence to touch down in the left hand corner.
Bernard landed a brilliant conversion for 17-3, with Michalak slotting over a penalty for offside shortly afterwards to make it 17-6 in front of a sold out 33 000 Chaban-Dalmas Stadium.
Michalak reduced the deficit further six minutes into the second-half as Bordeaux were penalised for a high tackle.
However, the metronomic Bernard added a penalty in the 49th minute for 20-9 but the visitors then scored 10 unanswered points to move within a point of the hosts.
Michalak slotted over another penalty followed by Habana's try which the mercurial Frenchman converted before being replaced by Matt Giteau.
Giteau it was who gave the visitors the lead for the first time in the match with a penalty 10 minutes from the final whistle and the visitors held on for a crucial four points.