Two goals in eight second-half minutes saw third-placed Lille deal a heavy blow to ten-man Paris Saint-Germain's Ligue 1 title hopes.
Javier Pastore put PSG in front in the 48th minute only for Mamadou Sakho to see red for a foul in the area, allowing the electric Eden Hazard to draw the sides level from the penalty spot with 20 minutes left. Nolan Roux converted the winning goal soon after.
The result leaves Montpellier five points clear at the summit, while Lille are now just two points adrift of today's opponents in the race for automatic qualification for UEFA Champions League football.
Hazard, watched by representatives of both Manchester United and Manchester City, was into the game in the opening minute, drawing a save from Salvatore Sirigu with an early free-kick. Another free-kick presented itself in the third minute and again Hazard worked the goalkeeper. This time the ball bounced back out to Tulio de Melo, whose reaction header was again saved by Sirigu.
Hazard and Sirigu continued to excel in the 19th minute, the Lille forward crossing for De Melo and the PSG keeper beating away the resulting diving header. PSG almost scored with their first decent attack just before the half-hour mark when Pastore beat Mickael Landreau only to hit the crossbar.
Just seconds later, Lille went even closer as Hazard struck from 20 yards, hitting the left post and then seeing the ball roll across the goal-line without crossing.
The visitors went in front just after the interval, though, when Landreau diverted Kevin Gameiro's cross to Pastore, who duly headed home. Landreau did stop Aurelien Chedjou from making it 2-0 and Lille made their opportunity count when Hazard converted from the spot following Sakho's foul on Roux.
Roux then turned match-winner when Hazard and De Melo combined to tee him up for a point-blank header in the 79th minute.