Mario Ballotelli took just seven minutes to score his first goal for new club Nice as he scored twice on his debut.
The Italian coolly scored from the spot early to put Nice into the lead.
But Marseille fought back, with former Premier League pair Florian Thauvin and Bafetimbi Gomis putting the visitors into the lead.
Balotelli then equalised, heading home in the 78th minute, before Wylan Cyprien scored a late winner to send Nice top.
The Italian was quickly deemed surplus to requirements at Anfield by Jurgen Klopp, after he returned from a season-long loan at AC Milan and was immediately frozen out, before ultimately ending up in Ligue 1 after a string of clubs turned down the chance to sign the wild forward.
Balotelli has quickly began to repay Nice's faith, though, as his lethal finishing ability and nonchalant swagger inspired them to victory in their derby clash, before he took a swipe at Klopp, Brendan Rodgers and his overall regret following his 2014 move to Liverpool.