Rennes, who faced anger from their fans after being knocked out by third division Quevilly in a French Cup semi-final last week, are fifth on 51 points.
The team finishing fifth will secure a Europa League playoff spot if fourth-placed Lyon beat Quevilly in the French Cup final on April 28.
Nice are 14th on 34 points, only one point above the relegation zone.
On Monday, the Roazhon Celtic Kop, reserved for Rennes's largest fans group, was empty in a demonstration of anger towards the players.
Rennes went ahead on 23 minutes when Julien Feret fired a low shot past David Ospina.
Tongo Hamed Doumbia doubled the tally one minute before the interval with a downward header, only for Francois Clerc to reduce the arrears shortly before the hour mark with a 20-metre strike.
Jonathan Pitroipa, however, put the result beyond doubt eight minutes from time with a fine chip.
On Wednesday, League Cup winners Marseille, who have nothing to aim for in Ligue 1, take on Caen, while losing finalists Lyon will bid to stay in the hunt for a Champions League play-off spot when they travel to Toulouse.