PSG's cash-rich Qatar owners have spent ?82 million ($107 million) on players this season and coach Antoine Kombouare and his players are under intense pressure to win the title for the first time since 1994.
After 19 games, they are halfway there, and Christmas will have a warmer glow after Montpellier, Lille and Lyon all failed to win on Wednesday.
PSG's goal was scrappy, but Kombouare - whose position has been under threat in recent weeks - will hardly care.
Nene floated over a corner in the 32nd minute and midfielder Mathieu Bodmer's header hit the post and bounced back off goalkeeper Stephane Ruffier's hand and into the net.
PSG had Italian goalkeeper Salvatore Sirigu to thank for a third consecutive clean sheet in the league, as he made superb saves from Max-Alain Gradel and Pierre-Emerick Aubameyang.
Montpellier led 2-1 but then conceded three goals in eight minutes as it lost 4-2 at Evian.
"It's not so much the result that's disappointing, it's the behavior of my players,'' Montpellier coach Rene Girard said. "Maybe we showed our limitations tonight. I'm very disappointed. Evian gave us a lesson in how to be aggressive.''
Although Lille moved within one point of Montpellier after drawing 4-4 at home to 10-man Nice, it surrendered the lead three times in an absorbing game which saw Nice equalize in the fourth minute of injury time.
"It feels like such a waste,'' Lille coach Rudi Garcia said. "We played like it was a friendly match in the first half. We would liked to have won the game, but we weren't good enough on set pieces.''
Lyon, meanwhile, was full of confidence after winning its last four league games but lost 1-0 at Valenciennes and missed the chance to overtake both Lille and Montpellier.
"This result stops us in our tracks,'' Lyon coach Remi Garde said. "With a bit of luck we could have got a point, but Valenciennes deserved to win the game. This just proves we're capable of the best and the worst.''
Montpellier took the lead early in the second half when Younes Belhanda scored from close range after goalkeeper Stephan Andersen had saved John Utaka's shot.
The lead lasted only five minutes as veteran midfielder Cedric Barbosa equalized against his former club, reacting quickly to clip the ball over keeper Geoffrey Jourdren.
Two minutes later, Giroud restored Montpellier's lead when he ran onto Belhanda's perfectly weighted pass and lobbed Andersen expertly for his 13th goal of the season.
But then Montpellier's defense fell apart as striker Saber Khlifa and defenders Cedric Cambon and Brice Dja Djedje all scored. The loss means Montpellier heads into the winter break without a win in its last three league games.
In Wednesday's other results, it was: Auxerre 2, Dijon 2; Lorient 0, Caen 0; Rennes 1, Bordeaux 0; Sochaux 0, Ajaccio 2, and Toulouse 0, Brest 0.
At Lille, Aurelien Chedjou's deflected strike put the champions in front, but Renato Civelli equalized in the 16th minute when he headed in David Hellebuyck's corner.
Joe Cole almost put Lille back in front moments later but his spectacular overhead kick went just over, and Nice goalkeeper David Ospina kept out Dimitri Payet's shot as Lille poured forward.
Cole restored Lille's advantage in the 27th with a superb strike, the former Chelsea midfielder swapping passes with defender David Rozehnal and hitting a first-time shot flew into the net.
But Nice stunned the home crowd with two goals before halftime, with Eric Mouloungui setting up both.
Mouloungui broke free down the right and dribbled his way into the penalty area, waited for defender Franck Beria to commit himself and played the ball calmly to Dja Djedje, who scored from close range.
Mouloungui then turned Chedjou inside out, and hit a fierce shot that 'keeper Mickael Landreau could only push straight to Dja Djedje, who tapped into the open goal.
Lille almost equalized straight after the break when Ospina beat away Eden Hazard's strike from outside the box, but then Mouloungui surged forward and hit a curling shot just over the top left corner.
The Gabon international was proving impossible to stop, whatever side of the field he found himself on.
In the 63rd, Mouloungui gathered the ball on the left, cut inside, poked the ball through Rozehnal's legs and smacked a rising shot just over.
But Mouloungui then got a second yellow card in the 69th for fouling Florent Balmont and was sent off.
Hazard equalized in the 76th when he collected substitute Ludovic Obraniak's pass, and Balmont thought he had scored the winner in the 88th, with Obraniak again the provider.
Defender Francois Clerc then made it 4-4 with virtually the last kick of the match.