PSG, which won the domestic treble last season, took the lead in the 41st when striker Edinson Cavani latched on to Angel Di Maria's quick pass and lobbed the goalkeeper from the edge of the penalty area.
A mix-up in PSG's defense resulted in midfielder Joseph Lopy getting the ball some 20 meters out and striking a low shot past goalie Gianluigi Buffon in the 70th.
Buffon came on at halftime after Alphonse Areola appeared to hurt his back. Di Maria was helped off the pitch by PSG staff in the 58th after hurting his ankle.
In the French league Tuesday, midfielder Faycal Fajr converted a penalty nine minutes into injury time to give Caen a 2-1 win over fellow struggler Toulouse and lifting the team provisionally out of the relegation zone.
Fajr and Saif-Eddine Khaoui both scored for the second straight match to help Caen move up to 16th place, one point behind Toulouse.
Khaoui scored with a rasping shot from outside the penalty area to put Caen 1-0 up after 18 minutes.
Forward Max-Alain Gradel underlined his worth to Toulouse with a penalty just before the break. Toulouse has mustered only 15 league goals and Gradel has scored six while providing four assists.
The match was initially scheduled for last weekend but moved at the request of authorities, with police resources stretched around the country amid a wave of anti-government protests.
(With inputs from agencies.)