Montpellier took a significant step towards their first ever Ligue 1 title by winning 2-0 at Rennes on Monday to restore their three-point lead over PSG with two games to play.
PSG had gone top on goals scored by winning 4-3 at Valenciennes on Sunday, but Montpellier are now in pole position ahead of a home game with reigning champions Lille next weekend that could decide the destiny of the title.
Rennes winger Jonathan Pitroipa hit the crossbar with an overhead kick after 13 minutes at Stade de la Route de Lorient but the visitors took the lead with their first attempt on target in the 26th minute.
John Boye's attempted clearance was blocked by Remy Cabella and fell for Souleymane Camara, who smashed home from close range to partially atone for his unsuccessful injury-time penalty in last week's 2-2 draw with Evian.
Montpellier's second goal early in the second half owed much to fortune, with Cabella's rasping low drive bouncing off the base of the post before rebounding into the net off prone Rennes goalkeeper Benoit Costil.
Despite the defeat, Rennes remain on course for a fifth-place finish - synonymous with a berth in the UEFA Europa League - although they now lead sixth-placed Saint-Etienne on goal difference alone.
Lille must beat Montpellier next weekend to stand any chance of retaining their title but they at least secured a Champions League place by comfortably winning 3-0 at home to Caen earlier on Monday.
Tulio de Melo opened the scoring from the penalty spot in the 26th minute after Eden Hazard was felled by Caen goalkeeper Alexis Thebaux and the Brazilian striker doubled his tally 10 minutes later by rising to head home from a corner.
Dimitri Payet made it 3-0 from Hazard's pass -- the Belgian's 15th assist of the season -- on the hour, before De Melo was denied a hat-trick when his half-volley cannoned back off the bar.
"(Finishing in the top three) was our ambition at the start of the season, but not the target," said Lille coach Rudi Garcia. "Now that we've got at least third place, we're obviously hungrier. We'll do everything to take second place, and maybe even jump into first."
Auxerre sank to the foot of the table after crashing 4-2 at home to Bordeaux, who opened the scoring through Yoan Gouffran after 13 seconds and were 3-0 up inside nine minutes thanks to a further goal from Gouffran and a Ludovic Sane header.
The defeat left Auxerre two points from safety, while Sochaux leapt from the bottom of the table to 17th place after an 85th-minute Sebastien Roudet strike secured a potentially priceless 1-0 win at home to Nancy.
Dijon sit second-bottom, a point above Auxerre and level with third-bottom Brest, after they registered a goalless draw at Lorient. Nice's trip to Toulouse also ended goalless, while Saint-Etienne's Europa League push was checked by a 0-0 stalemate at home to Marseille.