Zlatan Ibrahimovic's first goal since August was enough to seal the defending champions' ninth success on the spin in all competitions.
The Swede stepped up to convert from the spot after 15 minutes following a foul on Javier Pastore, keeping the pressure on leaders Marseille, who beat Nantes 2-0 on Friday.
Monaco's difficult season continued with a 2-0 loss at Rennes.
Aymen Abdennour inadvertently put the hosts in front with an own goal after 10 minutes, before Ola Toivonen fired home a close-range volley.
Montpellier were held to a 1-1 draw by struggling Caen, Mathieu Duhamel cancelling out Hilton's opener.
Although the result stretches Caen's winless run to five games, Patrice Garande's side are now out of the relegation zone and up to 16th.
Yet there was no such joy for Bastia, who dropped to 18th after losing 2-1 at Reims at the end of a week that saw striker Brandao given a jail sentence for a headbutt on Thiago Motta.
