Lille will lead the French league into the winter break after drawing 1-1 with Saint-Etienne on Wednesday.
Lille's main rivals failed to take advantage of the draw with Paris Saint-Germain and Rennes both losing away games and Lyon drawing. PSG fell 2-0 to Nancy and Rennes 1-0 at Caen, while Lyon drew 1-1 with Auxerre.
Lille, which has a game in hand, tops the standings with 32 points, one more than Paris Saint-Germain, Rennes and Lyon.
"I want to think about our superb first half of the season," Lille coach Rudi Garcia. "The league is very tight this season, but all big teams are there."
Lille striker Moussa Sow struck a season-high 14th goal in the 72nd minute, collecting Gervinho's cross into the box and outpacing United States captain Carlos Bocanegra before beating goalkeeper Jeremie Janot with a clinical finish.
Saint-Etienne was awarded a penalty three minutes later after Adil Rami fouled Bakary Sako, who converted from the spot to equalize.
In Nancy, Youssouf Hadji scored twice as the hosts ended PSG's run of 13 unbeaten matches in all competitions.
PSG dominated in the early stages as France striker Guillaume Hoarau created two chances within the first five minutes. Antoine Kombouare's team yet never recovered from Mamadou Sakho's dismissal in the 14th minute for a foul on Hadji.
Soon after, PSG striker Mevlut Erding's close-range shot was deflected for a corner. Hadji forced goalkeeper Apoula Edel into a good save with a precise shot at the near post in the 45th minute.
Hadji scored in the 66th minute with a chip over Edel, then doubled Nancy's lead from a rebound in the 83rd.
Rennes lost its fourth game this season after Caen midfielder Romain Hamouma struck the winner in the ninth minute with a curled right-footed drive from 20 meters.
Fifth-placed Marseille was held to a scoreless draw at promoted Brest. Defender Rod Fanni, who joined the defending champions last week from Rennes, injured his left thigh and was substituted by Fabrice Abriel after only 30 minutes.
It was the fifth straight game that Marseille had failed to win, leaving the team three points behind leader Lille.
"This is true that we are struggling to find the right pace at the moment. Fortunately, the other teams don't go much faster," Marseille coach Didier Deschamps said.
Despite the absence of the injured playmaker Yoann Gourcuff, Lyon dominated possession in the first half but had to wait until the 45th minute to open the scoring.
Auxerre goalkeeper Olivier Sorin blocked Michel Bastos' free kick, and Kim Kallstrom crossed the ball into the box for Auxerre defender Jean-Pascal Mignot to score an own-goal with his knee.
Lyon's central defenders were caught off guard immediately after halftime as Julien Quercia collected a through ball from Dennis Oliech to round goalkeeper Hugo Lloris and equalize.
Also, it was: Valenciennes 2, Toulouse 1; Monaco 2, Sochaux 1; Arles 0, Nice 0 and Bordeaux 2, Lens 2.
Struggling Lens looked poised to end Bordeaux's eight matches unbeaten run after first-half goals from Eduardo and Abdoulrazak Boukari but France midfielder Alou Diarra pulled one back in the 67th before Yoan Gouffran struck the equalizer from close range deep in injury time.
