Three-time champions Inter Milan face a battle to get through Europa League Group K after a second successive defeat.
Alassane Plea's goal earned Nice a 1-0 win over AS Nancy on Sunday that moves them top of Ligue 1.
Mario Balotelli scored twice as Nice beat Monaco 4-0 to go top of Ligue 1, while there were also wins for Lyon and Bordeaux.
Lyon missed the chance to climb up to third in Ligue 1 after they were held to a goalless draw against Marseille.
Mario Balotelli claims his ill-fated move to Liverpool was "the worst mistake of my life".
Mario Balotelli scored twice on his debut to inspire Nice to a 3-2 win over Marseille.