Cristiano Ronaldo has tested positive for Covid-19, Portugal's Football Federation confirmed on Tuesday.
The 35-year-old is said to be "doing well, without symptoms, and in isolation", with no further positive tests reported in the squad ahead of Wednesday's Uefa Nations League match against Sweden.
Former Manchester United and Real Madrid forward Ronaldo had played in both of Portugal's matches so far during the international break.
Ronaldo started against Spain in Lisbon, coming off late in the second half of the goalless draw, and then played the whole of the Nations League A3 fixture against France in Saint-Denis on Sunday.
The 35-year-old had scored in each of his Serie A appearances this season, including a brace in the 2-2 draw against Roma on September 27.
Ronaldo is now set to miss Juve's Serie A trip to Crotone on Saturday and their Champions League group stage opening game away to Dynamo Kiev next Tuesday.
He is also a doubt for Juventus' match with Barcelona on October 28, which was set to was set go head-to-head once again with his old rival Lionel Messi.
Ronaldo is the highest-profile footballer to test positive for Covid-19, which has killed over a million people since the start of the pandemic earlier this year.
Brazil forward Neymar, his Paris Saint-Germain teammate Kylian Mbappe and AC Milan striker Zlatan Ibrahimovic have also tested positive for the virus in recent weeks.
Portugal currently has 89,121 reported cases of Covid-19 with 2,110 deaths and 54,047 recovered. Its population is approximately 10.1 million.
The country initially won praise for its quick response to the pandemic, but, like most other European countries, has seen the number of infections rise again, concentrated in Lisbon and the country’s northern region, after a summer lull.