Rennes' Champions League play-off ambitions took a jolt on Friday following a 2-0 Ligue 1 defeat at Lille.
A Chris Mavinga own-goal and Dimitri Payet's second-half header saw Lille record their second straight league win and condemned Rennes to what could prove to be a costly ninth league defeat of the season.
The result moves Rudi Garcia's Lille up to eighth place in the standings on 37 points, while Rennes, who could have replaced Marseille in third spot with victory at Grand Stade Lille Metropole, stay fifth on 40 points.
Marseille can tighten their grip on the final Champions League place with victory against Valenciennes on Saturday.
French left-back Mavinga handed Lille the advantage when he deflected Ronny Rodelin's cross into his own net.
The visitors were dealt a further blow when key midfielder Romain Alessandrini had to be substituted after suffering a knee injury in a collision with Aurelien Chedjou.
Payet compounded Rennes' woes 15 minutes into the second half, nodding Salomon Kalou's precise cross into Benoit Costil's goal.