Having dropped off the pace of big-spending leaders Paris St Germain, Lille's chances of retaining the crown seem remote, but they at least used their game in hand to full effect, moving back to within six points of the summit.
Nolan Roux's late header proved enough for Lille, but they spent much of the match on the back foot before improving after the break.
Pierre-Emerick Aubameyang scored a hat-trick as two late goals guided St Etienne to a third successive home win, 4-2, and fourth place in Ligue 1, three points behind Lille.
Lorient took the lead through a Arnold Mvuemba penalty before two Aubameyang goals saw the home side take the lead.
Mathias Autret levelled for the visitors and a draw appeared likely before Bakary Sako scored two minutes from time with Aubameyang wrapping up victory, and his hat-trick, with a last-minute strike.
Livio Nabab scored the winner as Caen came from behind to bolster their survival prospects and leave Auxerre in the relegation zone mire with a 2-1 win.
Roy Contout put Auxerre ahead after an hour, but Caen drew level through Kandia Traore after 71 minutes and Nabab completed the fightback five minutes later.