Goals by Filip Djordjevic and Fernando Aristeguieta guided Nantes to a 2-0 Ligue 1 victory as Nice continued their poor record at the La Beaujoire-Louis Fonteneau.
Nice have won just once in Nantes in nearly 25 years but entered the game in good form having lost just once so far this season - to Lyon on the opening day - and were in search of a third successive win.
However, Djordjevic slotted home from close range after 27 minutes before Aristeguieta headed home to seal the points for Nantes with two minutes left.
A quiet opening to the match saw Jordan Veretout fire over before the hosts went ahead.
Issa Cissokho and Veretout combined to set up Serge Gakpe and although his shot was saved by Nice goalkeeper Mouez Hassan, an unmarked Djordjevic was on hand to poke the ball home.
Nantes almost doubled their lead three minutes before the break. Veretout forced a corner from which Cissokho powered a header at goal only for Hassan to punch the ball clear.
Nice almost levelled on the stroke of half-time when Eric Bautheac picked out Fabrice Abriel in the area but defender Chaker Alhadhur got back to counter at the last moment.
It was all Nantes in the second half and they almost got their second five minutes after the break.
Gakpe's driven corner was met by Veretout and his left-footed shot brought a magnificent stop from the impressive Hassan.
Vincent Bessat created space for himself and shot from a tight angle only for the ball to go wide before he provided a corner which was met by Lucas Deaux but his header went past the post.
Eventually Nantes wrapped up the points. Cissokho delivered a pin-point cross which Aristeguieta met with a perfect header to send the ball beyond Hassan.