Marseille centre-back Souleymane Diawara will be out for up to six months after undergoing surgery on a ruptured anterior cruciate ligament next week, the French club announced on Monday.
The 33-year-old Senegalese international was forced off after just six minutes of his side's 1-1 draw at Nice on Saturday after spraining his right knee in an early challenge.
"The operation, a ligamentoplasty, should take place next week," Marseille revealed, adding that "the period of unavailability for the player will be around six months".
Diawara was already suspended for the first leg of Marseille's Champions League quarter-final at home to Bayern Munich on Wednesday, along with goalkeeper and captain Steve Mandanda.
Marseille's draw at Nice ended a club-record run of seven defeats in all competitions but left them 13 points off the pace in the battle for Champions League qualification.
They will face Lyon in the French League Cup final on April 14.
Despite the gravity of the injury, and the length of the lay-off, Diawara struck a philosophical tone in an interview with French sports daily L'Equipe that appeared on Monday.
"Life goes on," he said. "I'm not taking this injury lightly. It's just that I also see what's going on in the news at the moment.
"You want me to complain? I play for one of the best French clubs, in a city that lives for football. I'll have an operation and then I'll do everything to come back.
"In September, I hope, even though we don't want to get ahead of ourselves."