One Santos player and eight employees have tested positive for COVID-19, the Brazilian Serie A club has said.
In a statement, Santos said on Monday all of those infected were asymptomatic but had been isolated as a precaution, and their names were not disclosed for privacy reasons, reports Xinhua news agency.
Santos added that antibody tests showed three other players had previously been in contact with the virus without knowing.
The results came after 24 players and 45 staff members were tested at Santos's training complex on Friday.
Sao Paulo state governor Joao Doria said last week that clubs could begin training on July 1, having been inactive since all sports were suspended in Brazil in mid-March.
Earlier on Monday, Sao Paulo FC said one of their players and an employee had tested positive for the virus.
Brazil has more than 1.1 million confirmed coronavirus cases, of which more than 51,000 have been fatal.