La Rochelle beat visiting Toulouse 30-7 in the French Top 14 on Saturday to end an eight-match losing streak against the 21-time champions.
The hosts' last victory over Toulouse, came in September 2019 in a run which included continental and domestic finals two years ago.
The hosts won without towering Australian lock Will Skelton who was out with a knee injury, as were ex-New Zealand scrum-half Tawera Kerr-Barlow and France centre Jonathan Danty, who is sidelined until at least the start of the Six Nations.
With heavy rain falling on the Atlantic coast, the home side led 16-0 at the break.
Romain Sazy bundled over for a try and Antoine Hastoy kicked a conversion and three penalties.
The dominance continued into the second half as the downpour eased. Pierre Boudehent slid over on the greasy surface just after the hour.
"The weather conditions played a role, but we managed to produce some rugby," said La Rochelle No. 8 Gregory Alldritt.
With six minutes left, Arthur Retiere claimed a late consolation for Toulouse, who lost for the first time in six games in all competitions but remain top of the table before two weeks of Champions Cup action.
Kyle Hatherell capped off a clinical performance for La Rochelle with a try with the clock in the red.
Alldritt said the team huddled at the end to focus on what lies ahead.
"To calm everyone down, the message in the huddle after the game was not to get ahead of ourselves. We've beaten Toulouse at home but we're not French champions because of it," the France international told broadcaster Canal+.
Earlier, Argentina winger Santiago Cordero scored his second try in two games as Bordeaux-Begles beat Bayonne 23-15 to take third place.
Cordero, 29, crossed after the break as France scrum-half and club captain Maxime Lucu kicked 13 points to send their side three points away from Stade Francais in second.
Yoram Moefana started at inside centre and the 22-year-old scored to push his claim to replace Danty for France in the Six Nations.
Lucu's side next head to South Africa's Sharks and welcome Gloucester in the Champions Cup over the next two weeks.
"We're just in January, there's five months left of the season, and after the Champions Cup we have two away games on the bounce," Lucu told reporters.
"We were in 11th place, we were in a sticky situation. We can't forget where we've come from," he added.
Elsewhere, former South Africa under-20s captain Jeremy Ward claimed his third try of the season as 14-time champions Stade Francais moved within three points of the league lead with a 26-7 win over Castres.
On Sunday, Racing 92 head south to champions Montpellier searching for their first victory since December 4. The home side's South Africa centre Jan Serfontein is set to make his first home appearance of the season.