Cristiano Ronaldo has tested positive for coronavirus, the Portuguese Football Federation (FPF) announced on Tuesday.
A statement from the FPF said 35-year-old Portugal and Juventus forward is “doing well, without symptoms, and in isolation”.
Ronaldo is away on national team duty with Portugal’s national team which takes on Sweden in a Nations League group game on Wednesday.
The remainder of Fernando Santos’ Portugal squad have tested negative for Covid-19 and are available for selection.
Portugal played out a 0-0 draw with France in Paris on Sunday and are top of the group, level on points with the world champions.
Portugal captain Ronaldo became the first European to score 100 international goals in men’s football when his side beat Sweden in the reverse Nations League fixture in September.
Being in quarantine means Ronaldo is also set to miss Juventus’ Serie A fixture at Crotone on 17 October and his side’s opening Champions League group game against Dynamo Kiev on 20 October.
The Italian champions then face Verona on 25 October.