Willian, who will remain with the team at their training base ahead of the final, scored Brazil's final goal in their 5-0 drubbing of Peru in the group stage and scored in their penalty shootout victory over Paraguay in the quarter-finals.
He was brought on for winger Everton at halftime in his side's 2-0 win over Argentina in the last four but tests on Wednesday revealed he had sustained a muscle injury.
Willian was a late replacement in the squad for Neymar, who was forced to miss the tournament in his home country after sustaining an ankle injury in a friendly against Qatar in June.
Willian is Brazil's only absentee for the final at the Maracana, where the five-times World Cup winners will be eyeing their first major trophy since lifting the 2007 Copa America.
(Reporting by Richard Martin; Editing by Peter Rutherford)
