Real Madrid says Éder Militão has tested positive for the coronavirus.
The reserve defender is likely to miss the team’s Champions League match against Inter Milan on Tuesday.
Madrid says all other players and staff members linked to the first team tested negative after tests carried out on Sunday.
The rest of the players were training normally.
Madrid is last in Group B after opening with a home loss to Shakhtar Donetsk and a draw at Borussia Mönchengladbach.
Militão has made three appearances this season. He is the second Madrid player to test positive for COVID-19 recently. Forward Mariano Díaz was the other.