Two first-half strikes from the champions' top scorer were enough to secure Laurent Blanc's men their seventh straight win in all competitions and maintain their impressive advantage over second-placed Monaco.
Monaco had briefly cut the gap back to five points earlier in the day with a 3-2 victory at Lyon, their fifth win from their last six matches.
Claudio Ranieri's men raced into an early two-goal lead thanks to goals from Valerie Germain and James Rodriguez before Jimmy Briand offered the hosts hope with a strike before half-time.
However, Dimitar Berbatov was on hand shortly after the restart to reinstate Monaco's two-goal advantage with a second goal since his January arrival in the principality before Briand netted what turned out be a consolation with 12 minutes left.
In Sunday's other match, 2012 champions Montpellier drew for the 16th time in the league this season after being held 1-1 at home by Bordeaux.
Les Girondins captain Henrique put the visitors ahead after 25 minutes but Vitorino Hilton levelled soon after with his third goal of the season to help Montpellier earn a valuable point for La Paillade in their battle for Ligue 1 safety.