PSG fell five points back of leaders Lyon on Saturday as the club slumped to a 2-1 defeat at Nice after conceding an 86th- minute goal to Valentin Eysseric.
The French giants have now claimed just one win from their last five league games, while Nice is unbeaten in five straight matches.
PSG was held without a goal into the second half thanks to some good goalkeeping from Nice's David Ospina.
And the hosts seized the advantage 15 minutes from time when Dario Cvitanich did some good work on the left to set up a close-range finish for Eric Bautheac.
Zlatan Ibrahimovic looked to have salvaged a point for PSG when he leveled the contest with a brilliant free kick eight minutes from time.
But Eysseric had other ideas as Fabrice Abriel's cross found his right foot and he sent a rocket of a volley past goalkeeper Nicolas Douchez.
Lyon 1, Montpellier 0
Lyon, France - A first-half strike from Bafetimbi Gomis was enough to extend Lyon's Ligue 1 lead to five points on Saturday as the club recorded a 1-0 win over Montpellier at the Stade De Gerland.
Gomis netted a hat trick in Wednesday's 4-1 win over Marseille, and he continued his good run of form with a goal midway through the first half.
Clement Grenier gained possession and played a through ball to Gomis, who slotted his shot past goalkeeper Jonathan Ligali for his ninth goal of the campaign.
Montpellier had the better of the play after halftime but Lyon goalkeeper Remi Vercoutre kept out a pair of powerful shots from Marco Estrada to preserve the win.
Bordeaux 2, Sochaux 2
Bordeaux, France - Bordeaux was denied three points by a late free kick from Rafael Dias as Sochaux snatched a 2-2 draw on Saturday at the Chaban-Delmas Stadium.
Sochaux took the lead in the first half through Loic Poujol, who headed home a free kick from Ryad Boudebouz to put the relegation battlers in front.
But Bordeaux equalized before halftime when a header from Yoan Gouffran struck Sochaux's Jerome Roussillon and found its way past goalkeeper Simon Pouplin.
Gouffran netted a goal of his own shortly after the restart when he scored from Jussie's flick, but Sochaux battled back to claim a point as Dias hammered a free kick into the upper corner of the net.
Evian 1, Nancy 1
Annecy, France - Nancy has now gone 15 games in Ligue 1 without a win after the club finished in a 1-1 draw with fellow relegation strugglers Evian on Saturday.
Evian scored first just before the break when Brice Dja Djedje tracked down a through ball and lobbed it over the head of goalkeeper Guy N'dy Assembe.
However, Nancy tallied a goal of its own early in the second half when Djamel Bakar found Yohan Mollo for an easy finish.
Evian nearly snatched the win in the last 20 minutes when a shot from Daniel Wass came back off the crossbar.
Valenciennes 1, Reims 0
Valenciennes, France - Valenciennes moved into the top five on Saturday after securing a 1-0 home win over Reims for its third win in five games.
Foued Kadir provided the lone goal six minutes into the match when he controlled a pass from Gaetan Bong and placed it neatly inside the far post.
Anthony Le Tallec tried to extend the lead for the hosts but he struck the post, while Reims came close equalizing in the 51st minute when Kamel Ghilas' volley crashed against the post.
Lille 0, Bastia 0
Lille, France - Mid-table sides Lille and Bastia played out a 0-0 stalemate at the Grand Stade Metropole on Saturday in a match that produced little in the way of chances.
The best opportunity for either side came in the first half when Lille's Dimitri Payet saw his free kick hit the post, while the first shot on target for either side came in stoppage time when Aurelien Chedjou's shot was kept out by Bastia goalkeeper Landry Bonnefoi.