A late equalizer by Monaco snatched a 2-2 result at Lorient on Saturday but it lost ground on Paris Saint-Germain in the French title race.
Monaco slipped to five points behind PSG, which beat Bordeaux 2-0 on Friday. The top two meet in a tantalizing clash in the principality next week.
Vincent Aboubakar headed Lorient in front in the 12th minute following good work by Kevin Monnet-Paquet down the right flank.
Monaco leveled three minutes from halftime when Valere Germain's weak shot beat Lorient goalkeeper Florent Chaigneau.
Lorient almost restored its lead immediately after the break but Bruno Ecuele Manga's effort was cleared off the line by Andrea Raggi.
The home side did go in front in the 73rd. Danijel Subasic's clearance fell to Aboubakar, who found Jeremie Aliadiere for a tap in.
Substitute Layvin Kurzawa rescued a point for Monaco with a low strike three minutes from time.
New Monaco signing Dimitar Berbatov was not in the squad.
Later, Saint-Etienne maintained its challenge for a Champions League berth as it comfortably beat relegation-threatened Valenciennes 3-0.
Former Valenciennes midfielder Renaud Cohade turned in a corner against his old club to break the deadlock in first-half stoppage time and Benjamin Corgnet all but sealed the result 10 minutes after the break.