Former Marseille president Pape Diouf died on Tuesday after contracting the coronavirus, the French club has confirmed.
Diouf, 68, was admitted to hospital in his native Senegal over the weekend and required breathing assistance.
The man who led OM from 2005 to 2009 was due to be flown to Nice this week but his deteriorating condition made that impossible.
Diouf was well-regarded in the French game and Marseille wished him well in his battle against COVID-19 via social media just hours before the news of his death.
Tributes have poured in for the former journalist and agent, with the likes of current OM stars Florian Thauvin and Maxime Lopez expressing their sympathies at the news, and former captain Habib Beye spoke of their "father-son" relationship.
Former counterpart Lyon's Jean-Michel Aulas also expressed sadness at losing a man he respected, while bitter rivals Paris Saint-Germain were quick to express their condolences.
PSG and France star Kylian Mbappe set aside the Classique rivalry to express his regret, as did many other clubs and players -- past and present.
Although Marseille did not win a domestic title under Diouf, he saw Les Phoceens twice finish second in Ligue 1 and the Coupe de France, but they did win the 2005 Intertoto Cup.
Last week, French football lost former player and coach Michel Hidalgo, who hailed from Marseille and served as OM's sporting director for five years between 1986-91, to non-coronavirus-related disease.
Hidalgo, 87, led France to their 1984 European Championship title.