Winger Florian Thauvin scored for the third time in the past four games to put Marseille ahead in the fifth minute, heading in Benjamin Mendy's cross from the left, and he almost scored again midway through the first half only to be denied by goalkeeper Simon Pouplin.
Zambia striker Emmanuel Mayuka leveled in the 60th with a superb strike from the right side of the penalty area into the top left corner.
Moments after the equalizer, Pouplin made a smart save to keep out forward Jordan Ayew's angled drive, then it was Marseille goalie Steve Mandanda's turn to shine as he flung himself to block midfielder Roy Contout's drive.
Sochaux remains in last place with just seven points.
Midfielder Lucas Deaux paid tribute to the large army of traveling Nantes fans after another impressive win for the newly-promoted side.
"When I see other teams playing on television, there are three or four blokes watching the away team. With our lot are three or four thousand and this inspires us," Deaux said. "Bordeaux didn't make the most of the 30 minutes or so when we struggled. After that, their chance had gone."
Midfielder Vincent Bessat opened the scoring shortly before halftime and defender Papy Djilobodji made it 2-0 in the 61st minute before Filip Djordjevic grabbed his eighth goal of the season shortly after to complete a convincing win.
"We scored three away from home without conceding any, so that's a good performance," Bessat said. "We weren't necessarily expecting to be in fourth place. We're on the crest of a wave, we work enormously hard and we haven't stolen any of our wins."
Bordeaux's form had improved recently but the defeat leaves it in 11th spot.
Lyon improved to seventh place after a dramatic last-gasp win away to bitter local rival Saint-Etienne.
Jimmy Briand headed in Yoann Gourcuff's cross deep into injury time to give Lyon a morale-boosting 2-1 away to bitter local rival Saint-Etienne.
Gourcuff came on as a substitute with 20 minutes remaining and jinked his way down the left flank before clipping over a cross toward the penalty spot, where Briand leapt superbly to nod the ball into the top left corner.
The win moved Lyon up to seventh place, while Saint-Etienne dropped to ninth spot.
Alexandre Lacazette gave the visitors the lead in the 48th minute, thumping in the rebound after Bafetimbi Gomis' header had been saved by goalkeeper Stephane Ruffier.
Winger Romain Hamouma equalized for the hone side midway through the second half after striker Brandao jumped higher than left back Henri Bedimo and nodded the ball down to Hamouma.
Max-Alain Gradel then the crossbar for Saint-Etienne in the 75th.