Lorient see off struggling St Etienne
The Brittany side opened the scoring with a superb free kick from forward Marama Vahirua on four minutes and doubled the advantage 12 minutes later through Argentine defender Franco Sebastian Sosa.
Lorient moved on to 24 points from 13 games, two points behind surprise leaders Auxerre who defeated Monaco 2-0 on Saturday.
"To see my team play tonight was a delight," Lorient coach Christian Gourcuff said after a convincing performance from a team with limited means and no big name.
"We're not that ambitious but we're not fixing ourselves any limits either," he added.
Champions Girondins Bordeaux and Olympique Lyon, who were in action on Saturday, lie second and third respectively, both a point adrift. Bordeaux lost 1-0 at home to Valenciennes and Lyon were held to a 1-1 draw at bottom club Grenoble.
Mid-table Nice beat Toulouse 1-0 courtesy of a second-half penalty by forward Loic Remy on Sunday and Montpellier then beat Lille 2-0 thanks to two goals by Colombian striker Victor Hugo Montano to move up to fifth.