Lille close gap with seventh straight win
The second-placed team's seventh consecutive league win put them on 37 points from 20 games. Champions Bordeaux, who have 43, welcome Olympique Marseille on Sunday.
Lille, who have scored at least three goals in each of their last seven games, opened the scoring with an angled shot by Poland's Ludovic Obraniak on four minutes.
Fellow midfielder Florent Balmont doubled the advantage with a header early in the second half and defender Franck Beria nodded a third before the visitors pulled one back through Turkey striker Mevlut Erding after 83 minutes.
"Lille are the best side we have played this season," PSG coach Antoine Kombouare told the television channel Canal Plus.
"It's frustrating because I have the feeling we can do better," added Kombouare after his side dropped to 10th. "It's the first time we've conceded three goals this season."
Lille coach Rudi Garcia was not totally satisfied either.
"I'm disappointed we conceded that late goal and a few players received knocks which could be a problem," he said.
The game was marred by crowd trouble, with the notoriously unruly PSG fans fighting among themselves in the stands and several being ejected by police.
There were also unsavoury incidents in Grenoble where the bottom club lost 2-1 to fellow strugglers St Etienne.
Some visiting fans threw seats at police who reacted by spraying teargas and the second half started 20 minutes late.
Surprise packages Montpellier, back in the top flight after a long spell in the second division, are seven points off the pace in third spot after beating lowly Nice 1-0.
Seven-times champions Olympique Lyon moved up to fourth, 10 points behind Bordeaux, with a 2-0 win at Nancy thanks to late goals from defender Cris and midfielder Maxime Gonalons.