Marseille's new striker Loic Remy has a heart problem and will not make his scheduled debut on Saturday.
Marseille, which also said it is set to sign France striker Andre-Pierre Gignac from Toulouse, made the announcement on Friday - just a day after Remy joined for a reported $19 million fee from Nice.
"We've decided to not play Loic Remy tomorrow (against Lorient) because MRIs yesterday evening showed a small problem," Dassier said. "The news this morning is encouraging but we made this decision because the player's health is what matters most."
The medical examination revealed a heart "abnormality," explained Christophe Baudot, the club's doctor.
"It's a mechanical problem," Baudot said. "More tests are scheduled for Monday so that we can give clear answers to Loic. He will play only when all the doubts are removed."
Remy, who has a five-year contract with his new club, said he never felt any specific pain throughout his career.
"I can't wait to be done with this and show on the pitch how proud I am to be here," Remy said.
Meanwhile, Dassier said Marseille had an agreement in principle with Toulouse over the transfer of Gignac.
The 24-year-old Gignac was the top striker in the French league in the 2008-09 season with 24 goals. A groin injury hampered him last season as he scored only eight league goals.
"I consider him the player in the French league with the greatest potential up front," Marseille coach Didier Deschamps said.
Toulouse currently leads the French league after winning its first two games while Marseille is yet to win a point.
Gignac will undergo a medical this weekend.
Marseille had been keen to strengthen its attack after the summer departures of Fernando Morientes, Bakari Kone, Mamadou Samassa and Senegal forward Mamadou Niang, the top striker in the French league last season.