The 35-year-old Juventus striker will miss Wednesday's UEFA Nations League game against Sweden but is "well, has no symptoms and is in isolation", the Portuguese federation says.
Portuguese football star Cristiano Ronaldo has tested positive for Covid-19.
The 35-year-old Juventus striker will miss Wednesday's UEFA Nations League game against Sweden but is "well, has no symptoms and is in isolation", Portugal's Football Federation said in a statement on its website on Tuesday.
The federation added that the rest of the Portugal squad had undergone tests as a result of Ronaldo's positive, but that they had all tested negative and would be available for the Sweden match.
Five-times world player of the year Ronaldo appeared in his side's 0-0 draw away to France in the Nations League on Sunday and Wednesday's 0-0 draw in a friendly at home to Spain.
He will now be doubtful for Juve's Serie A trip to Crotone on Saturday and their Champions League group stage opening game away to Dynamo Kiev next Tuesday.
In July, Ronaldo scored a double against Lazio to bring his tally to 51 Serie A goals since arriving in Turin in July 2018.
Earlier this year, Ronaldo scored for a record-equalling 11th consecutive Serie A game in his 1,000th professional match as Juventus extended their league lead with a 2-1 win over basement club SPAL.