Nice haS sacked manager Eric Roy after a run of one win in the last seven games left the club lying outside the Ligue 1 relegation zone on goal difference only.
Club president Jean-Pierre Rivere has replaced Roy with his assistant Rene Marsiglia ahead of Saturday's home game with St Etienne.
Rivere has urged the club's players to put in "more work, more rigorously", while telling Marsiglia he will be responsible for "pushing his team to victory".
According to a report in Nice-Matin, Roy - who took over the reins in March 2010 - will become general manager.
The 44-year-old played for the likes of Lyon, Marseille and English Premier League side Sunderland during his playing career, as well as having two spells with Nice from 1988-1992 and 2002-2004.
