Saint-Etienne remain in fourth despite losing 2-0 to Evian TG on Saturday.
It was the home side who started the match the stronger and Bakary Sako twice brought good saves out of Stephan Andersen after 15 minutes.
Saint-Etienne should perhaps have been ahead after 26 minutes when Laurent Batlles advanced on goal, but he fired wide before Andersen again denied Sako.
The away side took the lead with their first real attack of note after 38 minutes when Cedric Mongongu fired home from close range after a scramble in the box.
The home side continued to dominate the play in the second period, and Max Gradel saw an effort blocked after 51 minutes.
Evian remained a threat, however, and Sidney Govou brought a fine save out of Stephane Ruffier after 68 minutes.
It was the home side who continued to push for the equaliser, but they were caught on the break when Yannick Sagbo fired home to secure all three points for Evian.
Saint-Etienne remain in fourth spot in Ligue 1, while Evian have moved into 11th.
