Playing in the first of the day's fixtures and having won their first two games, OL began well in their bid to pull ahead of the pack when Corentin Tolisso tapped in after 20 minutes.
Northern summer signing Nicolas N'Koulou conceded a penalty from which Frederic Sammaritano equalised but Alexandre Lacazette scored his sixth goal in three games to restore Lyon's lead.
But the in-form striker then went off with a knee injury which could rob him of his France recall, having been named in the squad this week.
Julio Tavares made it 2-2 before Dylan Bahamboula and Pierre Lees Melou won the points for the home side.
Nice also failed to make it three wins from three when they were held to a 1-1 draw by Lille.
Vincent Koziello gave OGC an early lead but Franck Beria equalised, meaning PSG take on Monaco on Monday morning AEST with a chance to reclaim their familiar position on top of the pile.
That, for now, is occupied by Guingamp who won 2-0 at Nancy to move alongside Nice on seven points, and ahead on goal difference. Second-half goals from Mustapha Diallo and Thibault Giresse did the damage.
Caen beat Bastia 2-0 with second-half goals from Julien Feret and Herve Bazile, with Ronny Rodelin involved in both. Ivan Santini had a penalty saved.
Metz saw off Angers by the same scoreline with central defenders Simon Falette and Guido Milan each heading in a Renaud Cohade free-kick.
Rennes came from behind to earn a 1-1 draw with Montpellier, Adama Diakhaby cancelling out Daniel Congre's opener.