Midfielder Karim Ait-Fana twisted his way past two defenders in the area to score with an angled shot early in the second half. Marseille midfielder Benoit Cheyrou doubled the advantage by heading a corner into his own net 15 minutes from time.
Montpellier, back in the top flight this season after a long spell in the second division, moved to 42 points from 22 games, behind champions Bordeaux who looked a pale shadow of their best in a goalless home draw with lowly Boulogne.
"We know we're not at the same level as Bordeaux but we resisted well and even had a few opportunities," Boulogne coach Laurent Guyot told French television channel Canal Plus.
"Of course, we would have liked to win but we must remain humble. A draw here at Bordeaux is a very good result for us."
Belgium winger Eden Hazard lived up to his reputation as one of Ligue 1's most exciting players by resisting the challenge of two defenders to score Lille's winner after 23 minutes, putting them eight points off the pace.
