Former Arsenal and Chelsea winger Willian was unable to make his debut for Corinthians in Brazil on Sunday.
The club were eager to play the experienced attacker, but Brazil's health regulator threatened both the club and player with serious action.
Wilian has to complete a 14-day quarantine after arriving from England to complete his transfer to Corinthians.
Anvisa, Brazil's health regulator, says the player agreed to the quarantine time after he arrived from England.
"Ever since the start of the pandemic, the club has always complied with the sanitary rules imposed by different health bodies, even when some of them were confusing," Corinthians said in a statement hours before their match on Sunday.
"Therefore, we will comply without question."