RC Lens's unbeaten run in Ligue 1 came to an end when Jonathan David's penalty earned Lille a 1-0 home victory in the northern derby on Sunday.
Lens, who missed a penalty through Florian Sotoca and had not been beaten in their previous 17 league games, were overwhelmed physically by a bold Lille side.
The result left Lens in fourth place on 21 points from 10 games, five behind leaders Paris St Germain and four adrift of second-placed Lorient, who leapfrogged Olympique de Marseille after a 2-1 win at Stade Brestois earlier on Sunday.
Lille's win helped them to move up to seventh on 16 points.
In a high-octane first half in which each team picked up three yellow cards, Lens had the first opportunity to open the scoring in the 15th minute, but Florian had his penalty blocked by Lucas Chevallier after Jose Fonte had brought down Deiver Machado.
David was more precise for Lille when he converted a 44th-minute penalty after Massadio Haidara had fouled Benjamin Andre.
Lille pushed for a second goal after the interval and came close through Adam Ounas, David and Andre Gomes, but it was Lens who had the best chance when Alexis Claude-Maurice's 20-metre strike was tipped away by Chevallier.
It was Lens's first Ligue 1 defeat since April 10.
Earlier, Lorient's surprise run continued when they snatched a win at Stade Brestois courtesy of a Terem Moffi double.
Moffi cancelled out Romain del Castillo's opener before the break with a splendid shot into the top corner before sealing the win with his eighth goal of the season when he latched on to a cross from Yoann Cathline.
Monaco beat Montpellier 2-0 away to climb up to fifth, one point behind Lens.