Marseille reclaimed second place as they defeated Nice 2-1 and Rennes were held by Caen.
Lyon shocked; Marseille up to second as Caen hold Rennes
Lyon are just three points clear at the top after their stuttering form continued with a 2-1 loss at Nantes.
Frederic Piquionne put Lyon ahead on 44 minutes but lowly Nantes hit back in the second half to stun the league leaders.
Ivan Klasnic levelled on the hour mark and then stroked home the winner from the penalty spot just one minute from time.
Elsewhere, Marseille reclaimed second place as they defeated Nice 2-1 and Rennes were held by Caen.
An Olivier Echouafni own goal after 14 minutes set Marseille on their way to victory against fellow high-flyers Nice.
Mamadou Niang made it 2-0 from the penalty spot and Nice could not recover, despite pulling one goal back through Habib Bamogo early in the second half.
Rennes, beaten just once all season, had to come from behind to salvage a 1-1 draw at Caen.
Benjamin Nivet's opener for the home side on the stroke of half-time was cancelled out by Moussa Sow with 14 minutes remaining.
Lille and Toulouse also played out a 1-1 draw as Michel Bastos struck in the 90th minute. Mauro Cetto had put Toulouse in front after 64 minutes.
Having ended their dismal run of results last weekend, St Etienne continued their resurgence with a 2-0 victory against struggling Le Havre.
Dimitri Payet (75) and Bafetimbi Gomis (80) found the target for St Etienne.