Lyon moved to the summit with a 3-1 win at Guingamp on Saturday but their two-point lead was dashed after an excellent PSG rearguard in Marseille.
Andre-Pierre Gignac gave the hosts a 30th-minute lead and although the outstanding Blaise Matuidi levelled, the Marseille striker restored their advantage before the half-time break with a calm finish.
Laurent Blanc's men scored twice in the first six minutes of the second half, though, through Marquinhos and Jeremy Morel's unfortunate own goal.
And that proved enough for the champions, who weathered the storm to take a one-point lead in the thrilling race for the title over Lyon, while Marseille now sit five adrift of PSG.
Hamstring injuries to David Luiz and Thiago Motta could sour PSG's success, however, with a crucial UEFA Champions League tie against Barcelona to come this month.
The home fans created an incredible atmosphere before kick-off inside the revamped Velodrome and the raucous noise continued during a breathless first half.
A fast early tempo was not matched by quality football, at least initially, but Gignac's first goal brought the contest to life on the half-hour mark.
The forward beat Marquinhos at the back post with a firm header from Dimitri Payet's excellent cross which saw goalkeeper Salvatore Sirigu beaten from six yards at his near post.
The news went from bad to worse for PSG, as David Luiz, who had only just returned from a hamstring problem, limped off with a similar injury.
But a piece of individual brilliance from Matuidi drew the champions level 10 minutes before the break as the midfielder cut inside Brice Dja Djedje before curling into the top-right corner from 18 yards, despite the best efforts of Steve Mandanda who got a hand to the strike.
Marseille would head into the half-time break ahead, though, as a quick counter-attack saw Alaixys Romao's tackle fall for Gignac, and the forward calmly slotted past the onrushing Sirigu from 18 yards.
Gignac was only denied a first half hat-trick by Sirigu in stoppage time, and that save would prove crucial after the break.
Shortly after Payet curled wide for Marseille, PSG levelled, with Marquinhos on hand to restore parity in the 49th minute, making the most of a stroke of luck after Zlatan Ibrahimovic's mis-hit free-kick landed in his path.
And just two minutes later, PSG had the lead, as Pastore broke down the left and saw his deflected cross - intended for Ibrahimovic - turned into his own net by the unlucky Morel.
An eerie silence followed and Marseille seemed stunned, as Ibrahimovic wasted a free header before Matuidi and Pastore went close again.
Their second half domination continued right until the final whistle, but attacking verve was tempered as key midfielder Motta limped off in the closing stages.
