A last-gasp equaliser from Guillaume Hoarau denied Lyon what would have been a memorable victory in a thrilling contest at the Stade de Gerland.
Three goals in six first-half minutes had stunned the league leaders Paris Saint-Germain as Lyon looked to have grabbed the chance to overtake Marseille.
Everything seemed to be going according to plan for Carlo Ancelotti's men when Hoarau opened the scoring for the visitors, netting his second goal in as many weeks after 21 minutes.
Bafetimbi Gomis then levelled matters in the 34th minute, before Lisandro Lopez put the hosts in front two minutes later.
Brazilian wide man Michel Bastos then made it 3-1 in the 40th minute, with the league leaders left reeling.
PSG got back into the game when winger Nene cut the deficit just before the break with a penalty.
However, Jimmy Briand restored Lyon's two-goal advantage after 57 minutes.
A 73rd-minute strike from substitute Marcos Ceara gave Les Parisiens hope. PSG poured forward in search of the equaliser during a nervy last 15 minutes for Lyon.
Hoarau broke Les Gones' hearts in the fourth minute of added-on time when he powered a header past Hugo Lloris in goal to spark jubilant celebrations from the PSG bench.
However, the result still means PSG, who face Ajaccio at home next week, occupy second place in Ligue 1 and trail Montpellier HSC by two points.
Lyon, who have now gone four games without a win, travel to the Stade Marcel Picot next week to take on 18th-place AS Nancy.
