An obligatory Zlatan Ibrahimovic strike set Laurent Blanc's team on their way inside six minutes on Saturday before Ezequiel Lavezzi added a brace - one goal either side of half-time - to edge ever closer to a second straight league title.
Second-placed Monaco also won as Dimitar Berbatov netted his first for the club in a 2-1 victory over struggling Sochaux.
The Bulgarian struck after six minutes and then won a penalty for James Rodriguez to convert on 54 minutes.
That proved crucial as Sochaux pulled a goal back late on, Edouard Butin scrambling in while he laid on the ground, although Jordan Ayew's petulant kick on Andrea Raggi ended any thought of a comeback as the on-loan striker saw red.
Defeat for Sochaux was made worse as relegation rivals Evian and Valenciennes both won on Saturday, to leave them eight points from safety.
Cedric Cambon scored the only goal of the game as Evian moved five points clear of the drop zone with a 1-0 win over Guingamp while VA boosted their survival hopes with a 2-1 win over fellow strugglers Rennes.
After a goalless first half, Ola Toivonen gave Rennes the lead only for Mathieu Dossevi and Abdul Majeed Waris to turn the game around, the latter following up after his penalty was saved.
The win leaves Valenciennes on 25 points and still in the third relegation place, five points behind Evian and six adrift of their opponents - who had Jean-Armel Kana-Biyik sent off for conceding the penalty for the winning goal.
Sigamary Diarra struck a last-gasp equaliser as whipping boys Ajaccio denied freefalling Nantes what would have been their first victory in eight matches.
Nantes had taken just two points from a possible 21 to slump to within two spots of the drop zone, but they looked to have finally secured a win as goals from Serge Gakpe and Filip Djordjevic overturned Mehdi Mostefa's early opener for Ajaccio.
However, with victory seemingly in their grasp, the 2001 French champions were denied right at the death when Diarra slotted home two minutes into stoppage time as the match finished 2-2.
In the day's other game, Wissam Ben Yedder's superb solo goal completed a remarkable Toulouse comeback as they beat Reims 3-2.
Le Tefece trailed to two first-half penalties, from Grzegorz Krychowiak and Nicolas de Preville, as visitors Reim looked to keep themselves in touch with the European qualifying places.
But Alain Casanova's side roared back with three goals in the last 15 minutes, Serge Aurier and Eden Ben Basat drawing them level before Ben Yedder slalomed through in the 88th minute to snatch all three points.