The defending champions appeared to be heading for only their second league defeat of the season when Mali striker Mustapha Yatabare put the hosts ahead six minutes from time with a header from Rachid Alioui's corner.
However, Jocelyn Gourvennec's men were denied a famous victory just three minutes later when Alex powered home Lucas Moura's delivery to rescue a point that moves PSG six ahead of Monaco, who host Marseille on Sunday.
At the other end of the table, Montpellier boosted their survival hopes with a 3-1 home win over Nice that puts the 2011-12 champions six points clear of the drop zone.
On loan Milan striker M'Baye Niang opened the scoring after 31 minutes, the 19-year-old slotting into an empty net after collecting a square pass from Anthony Mounier.
Captain Hilton doubled the lead nine minutes into the second half and, although Nice forward Alexy Bosetti pulled one back for the visitors, victory was ensured with an emphatic finish from Souleymane Camara in the closing stages.
A last-gasp goal from midfielder Vincent Nogueira earned Sochaux a 1-1 draw at bottom club Ajaccio, who were denied just their second league win of the campaign.
Christian Bracconi's side looked to be on course to take all three points when Benjamin Andre put the Corsicans ahead with a close-range strike, only for Nogueira to stun the hosts as he turned home a deflected corner with last kick of the game.
Relegation-threatened Valenciennes failed to secure a third straight league win, but came from behind to claim a 1-1 draw with Lorient.
An own goal from defender Saliou Ciss gave the visitors the advantage six minutes before the break, however, striker Gregory Pujol salvaged a point for Ariel Jacobs' men with a looping header after 52 minutes.
Elsewhere, Nantes and Reims played out a 0-0 draw, while the game between Toulouse and Bastia was postponed due to torrential rain.
