PSG are chasing a third consecutive sweep of domestic honours but finished the weekend three points behind Ligue 1 leaders Monaco, who also have a game in hand, and played the last moments in Nice with only nine men after they had two men sent off in quick succession.
Sublime Cavani leads Monaco chase
Nice, still unbeaten at home this season, stay third but are now just three points behind PSG and both have only three games left to play.
Wayward Italian striker Balotelli, restored to Nice's starting line-up after a typically sticky spell of injury and suspension, prodded over from close range on 20 minutes after PSG's offside trap failed.
He should have done better and six minutes later he did, shrugging off a weak challenge before unleashing an unstoppable strike from the edge of the box that whistled into the bottom corner.
Matuidi keeps PSG hot on Monaco's heels
Unai Emery's PSG, who came into the top-of-the-table encounter on an excellent unbeaten run since their Champions League collapse at Barcelona early last month, enjoyed plenty of the ball in the first half but did little with it.
If Balotelli's strike was good, Pereira's just minutes after half time was even better, as the Portuguese winger curled the ball beautifully into the top corner.
The reigning champions appeared down and out and the game turned increasingly ugly, with several skirmishes breaking out.
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