Lille suffered a second successive defeat and squandered vital ground in the French title race when Saint-Etienne grabbed a 2-0 Ligue 1 victory.
The result left Lille, who ended the game with ten men after a red card for midfielder Florent Balmont, in third place in the table, seven points behind leaders Paris Saint-Germain and having played a game more. Saint-Etienne remain fourth, three points behind Lille, thanks to a timely win which followed a midweek Coupe de France exit at the hands of fourth division Cannes.
Lille had lost 2-1 to Reims last weekend and fell behind after 55 minutes on Friday when Brazilian striker Brandao headed in at the far post from a cross by Algerian defender Faouzi Ghoulam. Six minutes later it was 2-0 with Franck Tabanou slotting the ball home after Lille keeper Vincent Enyeama had saved from Romain Hamouma.
Lille then had to play the final 30 minutes of the match with ten men after Balmont was red-carded for aiming a volley of abuse at the referee, who he believed should have ruled out the goal.
On Sunday, leaders PSG welcome Nantes to the capital where a win could give them an eight-point lead over Monaco should the second-placed side lose at Toulouse.