Hatem Ben Arfa scored twice, including a superb solo effort, as 10-man Nice ended St Etienne's five-match winning run.
Fabinho scored a controversial penalty in the fifth minute of stoppage time as Monaco came from 2-0 down to win 3-2 at Ligue 1 basement boys Montpellier.
Paris St Germain preserved their unbeaten start to the season thanks to Edinson Cavani's late equaliser at Reims.
Montpellier climbed off the bottom of Ligue 1 but have still not scored a goal following a 0-0 draw at Troyes, while Reims went top with a 4-1 win over Lorient.
Blaise Matuidi scored his second goal of the season to secure Paris St Germain a 1-0 win at bottom side Montpellier.
Monaco secured a comeback victory in their Ligue 1 opener, but there was defeat for Marseille before manager Marcelo Bielsa resigned.