Defending champions Marseille cut the lead at the top to three points with two games to play but Lille's goal difference is seven better than their rivals if they finish on the same number of points.
Marseille led through the in-form Loic Remy on 14 minutes before Lamine Kone's header from a corner and a goal from Ligue 1 joint-top scorer Kevin Gameiro put Europa League hopefuls Lorient in front.
Substitute and former Lorient striker Andre-Pierre Gignac grabbed a late equaliser for Didier Deschamps' side but it made little difference to the picture at the top.
The capitulation, the latest during Marseille's run-in, comes despite their vast experience compared to Lille.
A home victory on Wednesday will secure a first championship since 1954 for this term's surprise packages Lille, who won the French Cup on Saturday by beating Paris Saint-Germain.
RENNES JOY
The northerners, nicknamed the Mastiffs, are now on the brink of a double which fans would not have even dreamed about at the start of the season.
Fifth-placed Stade Rennes confirmed their place in the Europa League with a 2-1 win at St Etienne, whose European hopes now look improbabley.
Racing Lens were relegated from Ligue 1 after a 1-1 draw at fellow strugglers Monaco.
Lens will join already relegated Arles-Avignon in the second division next term with the final relegation place still to be determined with two rounds of matches left to play.
Monaco thought they had won thanks to Benjamin Moukandjo's 14th minute goal but Raphael Varane struck in injury-time to send the principality side to third-from-bottom.
AS Nancy won 3-0 against Nice to climb to fourth-from-bottom, a point above Monaco.
