Filipo Nakosi dived over the line with two minutes left as Toulon beat reigning champions Castres 28-27 on Sunday for a first Top 14 victory of the season.
Yet their joy was tempered by a red card for captain Mathieu Bastareaud, for thumping an opponent on the ground, and injuries that forced off fly-half Rhys Webb and scrum-half Anthony Belleau.
"The season is launched," said Toulon backs coach Sebastien Tillous-Borde. "We managed to go and get them with a guy less after the red card."
For champions Castres, it was a first defeat of the season. While Toulon lost Bastareaud with 10 minutes left, Castres played most of the last 20 minutes with 14 men because of two yellow cards.
The Castres defeat left Clermont, who beat Stade Francais on Saturday, as the only club with three victories after three rounds and four points clear at the top.
The Toulon victory lifted the big-spending club off the bottom of the table.
"Winning is good," said Toulon lineout coach Juan Martin Fernandez Lobbe. "It heals."
In a first half that sometimes resembled fast-break basketball, No. 8 Liam Messam gave Toulon the lead in the fourth minute as the home pack drove him to the base of a post.
Winger Martin Laveau finished a sweeping Castres attack, before lock Steve Mafi raced through the Toulon defence after a turnover near midfield and found scrum-half Rory Kockott to score.
Two penalties and a drop goal by Benjamin Urdapilleta pulled Toulon clear before flanker Stephane Onambele struck back with a try for the home team.
The second half was more traditional rugby trench warfare on a surface that began to cut up badly.
The home pack shoved prop Sebastien Taofifenua over the line in the 49th minute.
Two more Castres penalties left the visitors four ahead and they held out after Tudor Stroe received a yellow card for bringing down a maul in the 62nd minute.
Bastareaud dived into a ruck as Castres turned over the ball and smashed an arm into Christophe Samson, who was on the ground. At some point in the chaos, the Toulon centre took a knee in the face. He saw red while Samson saw yellow.
Playing 14 against 14, Toulon won a penalty with five minutes to play and opted to take three points, with Louis Carbonel's successful kick cutting the gap to one point.
With two minutes left, hooker Guilhem Guirado broke through the Castres defence and the ball reached Nakosi alone in space and the winger sped away and dived over to score the match-winning try, despite Carbonel's missed conversion.
"When you lead after 78 minutes and concede a try at the end, it's hard to swallow," said Castres backs coach Joe El Abd. "But in the second half we did not have control and at the Mayol you pay dearly."
Earlier on Sunday, resurgent Pau registered an impressive away win with a hard-fought 24-21 victory over Grenoble at a sunny Stade des Alpes.
First-half tries from Jesse Mogg and Julien Blanc paved the way for Pau, before Grenoble showed tremendous fighting spirit to slug their way back into the game and earn a losing bonus point.
"An away win is always a good sign but this one shows just how good this team is," said Pau's Australian coach Simon Mannix, who led the team into the top flight four seasons ago.