In a meeting of second-versus-third, the home side began strongly and took an early lead through Mounir Obbadi – who finished off a swift move after good work from Dimitar Berbatov and Valere Germain.
Lille hit back impressively, though, and levelled through a stunning counter-attack.
Salomon Kalou broke forward with pace before finding Ryan Mendes, whose ball left Divock Origi with the simplest of finishes.
The result further dented Monaco's already-faint hopes of catching table-toppers Paris Saint-Germain – who boast a 10-point advantage at the summit.
But its significance was perhaps greater for those just below, with both Saint-Etienne and Lyon winning.
After a goalless first half against second-bottom Sochaux, Saint-Etienne came out firing as substitute Mevlut Erdinc and Franck Tabanou struck quickly after the restart.
Edouard Butin pulled one back in the 66th minute but, after Cedric Bakambu was sent off for a second bookable offence late on, Erdinc sealed a 3-1 win that leaves Saint-Etienne just three points adrift of Lille.
Lyon, who sit as many points further back, were far less exciting in sealing a 1-0 success over Guingamp, Bafetimbi Gomis grabbing the only goal in the 46th minute.
