Joao Cancelo will play no part at Euro 2020 after he tested positive for coronavirus, with Diogo Dalot called up as a replacement.
The 27-year-old is part of the Selecao's playing squad for the summer tournament and had been expected to play an important role in their hopes of retaining the European trophy.
But those ambitions have been dashed, with Portuguese outlet Diario Record first reporting that Cancelo has contracted Covid-19 and has been placed in isolation.
Portugal then added a statement, confirming: "Under-21 international Diogo Dalot will join the National Team's delegation in Budapest to prepare for his debut at Euro 2020.
"The AC Milan player will replace João Cancelo, who tested positive for covid-19 following a rapid antigen test carried out this Saturday by the FPF Health and Performance Unit."
Cancelo was tested on Saturday evening and the results came through on Sunday morning confirming the diagnosis, when Hungarian health authorities were informed of the illness immediately.
The rest of his teammates and coaching staff have all been tested too, with everyone other than Cancelo producing negative results.
The Manchester City defender, who is in a good condition, has been placed in isolation and will remain so until returning a series of negative test results or until his enforced quarantine comes to an end.
Manchester United defender Dalot has replaced him in the squad as Portugal turn their attention towards Tuesday's all-important opening tie with one of the many host nations, Hungary.
Fernando Santos' players will be desperate to get off to a winning start in Group F as they later face Germany and France in the final two matches in a quartet which has been dubbed the Group of Death.
Portugal will need their strongest team available for their three group stage matches if they are planning to qualify for the knockout rounds and retain the trophy, having beaten France in the final to win the competition for the first time back in 2016.
Cancelo is not the first player to test positive for Covid-19 at the European Championship. An outbreak spread throughout the Spain squad, with Diego Llorente and Sergio Busquets testing positive earlier in the week.