The top four all won as Ligue 1 returned from its winter break but it is Lille who hold a one-point lead over Paris St Germain, Rennes and Lyon.
Goals from Gervinho and Moussa Sow propelled Lille to a 2-0 victory away to previously in-form Nice.
Ludovic Giuly netted the winner as Paris St Germain overcame Sochaux 2-1 at Parc des Princes.
Mamadou Sakho's opener for PSG had been cancelled out by Modibo Maiga but Giuly struck to secure all three points.
Bottom club Arles were no match for Rennes as a brace from Yasine Brahimi and further efforts from Alexander Tettey and Yann M'Vila clinched a 4-0 success.
Lyon extended their unbeaten run to 13 matches as Bafetimbi Gomis (2) and Kim Kallstrom found the target in a 3-0 win over Lorient.
Lens eased their relegation worries and denied St Etienne fifth place after coming from behind to win 2-1 courtesy of a Sebastien Roudet penalty and Loic Perrin own goal.
Struggling Caen also claimed a crucial result as they shrugged off Thomas Heurtaux's dismissal to beat Brest 3-1.
Benjamin Nivet, Youssef El Arabi and Romain Hamouma got their names on the scoresheet for Caen, while Bruno Grougi netted a penalty for Brest.
Monaco now find themselves in the bottom three despite beginning life under new manager Laurent Banide with a creditable 1-1 draw at Auxerre as Julien Quercia's opener for the hosts was equalised by Adriano Pereira.
Valenciennes surrendered a 1-0 lead given to them by Mathieu Dossevi as Olivier Giroud and Abdelhamid El Kaoutari scored to give Montpellier a 2-1 victory.
Franck Tabanou's goal gave Toulouse a 1-0 triumph at home to Nancy in the day's final game.