Brazilian World Cup-winner Ronaldo tested positive for Covid-19 on Sunday, forcing him to cancel his appearance at celebrations for the 101st anniversary of his first-ever team, Cruzeiro, the club said.
The 45-year-old ex-striker "is fine, with light symptoms, and will now undergo a period of rest and social isolation, in line with medical advice", Cruzeiro, who Ronaldo bought last month, said on Twitter.
Ronaldo, who starred in Brazil's 2002 World Cup win and was thrice voted FIFA World Player of the Year, announced on December 18 he was buying a controlling stake in recently struggling Cruzeiro, where he made his professional debut in 1993 at age 16.
He scored 56 goals in 58 matches for the Belo Horizonte-based club before going on to a glittering career in Europe at PSV Eindhoven, Barcelona, Inter Milan, Real Madrid and AC Milan, winning the Ballon d'Or in 1997 and 2002.
Ronaldo was also in Brazil's 1994 World Cup-winning squad and scored eight goals in seven matches when the Selecao won the title again in 2002.
He ended his career at Sao-Paulo based Corinthians in 2011.
Mired in financial strife, Cruzeiro finished 14th in the Brazilian Serie B last season.
Globoesporte.com reported Ronaldo paid 400 million reais (about $72 million) to become the club's majority shareholder.
He also has a controlling stake in Spanish club Real Valladolid, who were relegated to the second division last season.