Montpellier overcame Dijon 5-3 as Olivier Giroud grabbed a hat-trick to help them recover from a two-goal deficit while Lyon beat Nancy 3-1 thanks to three first-half goals in an eight-minute spell including a Michel Bastos double.
Lille grabbed a 3-1 comeback win at AJ Auxerre with late goals by Dimitri Payet, substitute Ireneusz Jelen and Mathieu Debuchy as the champions, who started with Joe Cole and Eden Hazard on the bench, moved up one place to fourth on 19 points.
Montpellier trailed to Benjamin Corgnet's double after 11 minutes but the hosts fought back with striker Giroud netting a treble to become the league's top scorer on seven goals.
Montpellier, who have Ligue 1's best attack with 22 goals, looked set to snatch top spot on goals scored but Dijon striker Thomas Guerbert's last-minute strike left PSG top.
Lyon, who welcomed back defender Cris from a long-term injury lay-off, were quick off the mark as Michel Bastos' brace and a goal by Bafetimbi Gomis between the 25th and 32nd minutes gave the seven-times champions a 3-0 lead.
But sports director Jose Anigo would not blame his team. "We tried to play and we showed character and solidarity when we were down to 10 men," he told the club's website.
"Arsenal will be another game. It's not the same competition, there's no need to motivate the players."
