Troyes pulled themselves to within a point of Montpellier and four of Ajaccio, after their impressive win.
Nicolas Gousse had the home fans celebrating early when he dispatched his spot-kick past Gregory Wimbee, who dived the wrong way, in the third minute.
The home side continued to have the better of the contest, but could not make their early superiority count.
Just before the hour mark Troyes doubled their advantage when Karim Ziani crossed for Rafik Saifi to fire home, following Gousse's dummy in the middle.
The win was only Troyes' fifth so far this season, for the side who have scored the least goals in Le Championnat this season.
Le Championnat match stats:
Troyes 2-0 Lille
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