Nice returned to the top of Ligue 1 after Valentin Eysseric's strike against his former club sealed a 1-0 win at Saint-Etienne.
Eysseric, who spent last season on loan with Saint-Etienne, scored the winner on 63 minutes, firing a left-footed strike into the top corner after Jordan Veretout had lost possession in a dangerous area for the hosts.
Nice's victory - which came without the suspended Mario Balotelli and injured captain Paul Baysse - sees them restore a three-point gap over Monaco and Paris Saint-Germain at the top after both of their title rivals had won their games.
Lucien Favre's men had suffered their first league defeat of the season away to Caen last time out and avoided losing two straight league games - something they have not done since April 2015.
Ninth-placed Saint-Etienne have now won only one of their last six matches after a display that only saw them register one shot on target.
Alassane Plea fired off-target with two late opportunities and was then denied by home goalkeeper Stephane Ruffier as Nice sought a second goal.
The visitors' main scare had come early on, when Dante almost scored an own goal with a sliced clearance.