Paris St Germain saw its lead at the top of the Ligue 1 standings slashed in half after it suffered a surprise 3-2 defeat at lowly Sochaux while closest challenger Lyon thrashed Bordeaux 4-0 away from home.
PSG had looked to have taken a stranglehold on the title race after a run of four successive victories saw it open a six-point gap at the summit going into this weekend's fixtures.
However, with new signing David Beckham's debut still on hold while he gains match fitness and the in-form Lucas Moura injured, Carlo Ancelotti's men came unstuck against relegation-battling Sochaux at the Stade Bonal.
Alex gave the league leaders a 29th-minute lead but Sochaux hit back soon after to level through Sebastian Roudet before Giovanni Sio put the home side ahead in the 54th minute.
An enthralling encounter looked to have swung back the Parisians' way when they equalized through Blaise Matuidi 14 minutes from time but, rather than big-spending PSG going on and finding a winner, it was Sochaux who snatched a deserved win thanks to substitute Cedric Bakambu's goal six minutes from time.
That defeat meant PSG's advantage at the top of the table had been cut back to three points by Lyon, which saw off Bordeaux earlier in the day.
Two goals by Clement Grenier, one from the penalty spot, and further strikes from Alexandre Lacazette and Gueida Fofana earned Lyon its first four-goal victory at the Stade Chaban-Delmas since 1977.
In Sunday's other match, fifth-placed St Etienne was held to a 1-1 draw at struggling Reims.
St Etienne took a 10th-minute lead through Pierre-Emerick Aubameyang but Gaetan Courtet salvaged a point for Reims with an equaliser 14 minutes from time.