The Brazilian midfielder converted a cross from Jeremy Menez in the 42nd minute and doubled the lead in the 90th with a long-range strike inside the far post.
"That's our fifth straight win in the league," PSG coach Antoine Kombouare told the club's website. "Those matches are very complicated. We were facing a promoted side that came here with nothing to lose. We were the big favorite and therefore had to win. And we got the job done."
Meanwhile, defending champion Lille rallied past Lyon 3-1 to climb to third place, four points off the pace, and Rennes beat mid-table Auxerre 1-0 to take fourth place.
"Lyon troubled us with its attack in the first half," Lille coach Rudi Garcia told Canal Plus television. "We played well in the second half. What's more, we scored on set pieces, things on which we are working and were not very efficient."
In Lille, Jimmy Briand collected a pass from playmaker Yoann Gourcuff to slip the ball through the legs of goalkeeper Mickael Landreau from a tight angle and put Lyon ahead in the 22nd.
Lyon nearly added a second goal in the 33rd when Michel Bastos found Bafetimbi Gomis inside the area. But the Lyon striker chested the ball down only to fire wide from 10 yards.
Lille equalized on the stroke of half-time with a backheel flick from Senegal striker Moussa Sow. Lyon goalkeeper Hugo Lloris spilled a header from Marko Basa from a corner and Sow followed up to score.
Lyon faded in the second half as Lille dominated possession. Basa outjumped Lyon defender Bakary Kone in the 64th to head home a free kick from Dimitri Payet and give the hosts a 2-1 lead.
Sow charged down the left flank on a counterattack to pull the ball back for Joe Cole, who slid home from six yards in the 83rd.
"It's disappointing that we were a bit passive on two set pieces," Gomis said. "Unfortunately, you pay dearly against that kind of team."
Lyon slipped to fifth place, one point behind Rennes, which scored the only goal of the game against Auxerre when midfielder Julien Feret took a pass from Razak Boukari on a counterattack to beat goalkeeper Olivier Sorin in the 74th.
A minute earlier, Rennes defender Jean-Armel Kana-Biyik saved his team by clearing a lob from Auxerre striker Yaya Sanogo off the line.
"Teams ahead of us are impressive and it's not easy to keep pace with them," Rennes coach Frederic Antonetti told Canal Plus television. "We must win matches not to be dropped."
On Saturday, it was: Caen 1, Montpellier 3; Marseille 2, Ajaccio 0; Lorient 0, Toulouse 0; Saint-Etienne 1, Valenciennes 0; Sochaux 1, Evian 1; Nancy 1, Nice 0; Bordeaux 1, Brest 1.