Yoan Gouffran's fourth goal in as many league games proved enough for Bordeaux to humble Marseille and overtake Paris Saint-Germain, who lost 2-1 at home to nine-man Rennes on Saturday.
Bordeaux dominated the game from the outset and went the closest to opening the scoring in the 35th when Marseilles full-back Jeremy Morel saved a Henri Saivet header on the goal line.
Gouffran tapped in a Benoit Tremoulinas pass in the 52nd minute to extend Bordeaux's successful home run against opponents who have not won there since 1977.
The decimated visitors finished the match with a strike partnership of prospect Bilel Omrani, who had played only eight minutes in Ligue 1 before this game, and a 27-year-old amateur, Fabrice Apruzesse, who had never previously featured in the first squad.
Defender Lucas Mendes’s dismissal in stoppage-time only compounded Marseille’s woes.
Lyon, meanwhile, climbed to top spot in after they easily defeated Stade Reims 3-0 at Stade Gerland.
An Anthony Weber own-goal just before the break and two second-half strikes sent the seven-times French champions up to 25 points.
"I do not know for how long we will stay top, if it will be two hours, two days, two weeks or two months," Lyon coach Remi Garde said.
"There is no point in hiding our ambitions or delight being top at the moment.
"But I prefer when we are here because it brings confidence. We just enjoy being there. We will keep the top spot if we deserve it."
Lyon dominated possession throughout the first half but failed to create clear-cut chances and were condemned to harmless long-range efforts.
They broke the deadlock on the stroke of halftime after a great Anthony Reveillere effort in the box prompted centre-half Weber to accidentally poke the ball into his own net.
Lyon kept control of the game after the break, without really threatening goalkeeper Kossi Agassa.
Bafetimbi Gomis, who handed France a 2-1 victory in Italy in their friendly on Wednesday, eventually doubled the lead with 17 minutes to go with a powerful volley after a Steed Malbranque cross had hit the crossbar.
Lisandro Lopez wrapped it up late on.
Nice clinched a 1-0 home victory against Toulouse thanks to a second-half goal by striker Dario Cvitanich.
They climbed to 11th on 16 points while Toulouse, who have lost for the fourth consecutive time in all competitions, stay ninth on 19.