Atletico Madrid boss Diego Simeone has tested positive for coronavirus, the Spanish club has announced.
The Argentinian is asymptomatic but is now isolating at home.
Atletico is not in action as the new La Liga season begins this weekend after their late involvement in Europe last term, but are due to play Cadiz in a friendly on Tuesday.
A statement from the club read: "These Friday new PCR tests were carried out on the whole group and the manager has given a positive result.
"Fortunately, our manager is not showing any symptoms and is at his home isolating and fulfilling the required quarantine."
Friday's round of testing had been prompted after another member of club staff tested positive on Thursday.
Earlier this month, Atletico striker Diego Costa also tested positive for the virus.
Atletico's first league game of the new season, at home to Granada, is scheduled for September 27.
They reached the Champions League quarter-finals last term, losing to German side RB Leipzig in the last eight.