Celtic loanee Olivier Ntcham was hooked at half-time as Marseille were humiliated by fourth-tier Canet Roussillon in the French cup.
The midfielder joined the Ligue 1 giants in January on loan with an option to buy but the move immediately caused controversy.
An interview in which Ntcham professed his support for arch-rivals Paris Saint-Germain infuriated supporters but there was worse to come.
Coach Andre Villas-Boas offered his resignation as he insisted he had specifically said no to the Celtic midfielder.
The Portuguese was suspended and later fired by the club but Ntcham has struggled to break into the team.
Former Sevilla boss Jorge Sampaoli will replace him, but Nasser Larguet is in charge while he quarantines after flying in from South America.
The interim boss handed Ntcham a start in the Coupe de France on Sunday night but the match proved to be a historic disaster for Marseille.
OM were knocked out after a 2-1 loss to fourth-tier Canet Roussillon, who come from a town with a population of just over 12,000.
Jérémy Posteraro opened the scoring with a sublime free-kick, but Arkadiusz Milik equalised shortly before the break.
Ntcham was substituted for Saîf-Eddine Khaoui at half-time and could only watch as Yohan Baï struck a 71st minute winner.
Midfielder Boubacar Samara was frank after the final whistle, telling Eurosport: "It's shameful, we were s***."