Brazil Serie B midfielder Valdivia was substituted at halftime during his team Avai's match against CSA on Saturday after his club were notified he tested positive for Covid-19.
Avai said Valdivia took a test earlier on Saturday so that he could be cleared for the club's next fixture against Juventude on Tuesday.
But when the Brazilian Football Confederation (CBF) notified the club that he had tested positive, Saturday's game against CSA had already kicked off.
"At half time the CBF communicated... that Valdivia tested positive," Avai said.
The club said the player was asymptomatic.
"That is why Valdivia was substituted. The club is now reviewing his isolation and return."
The game finished 1-1.
Brazil reported 61,567 cases of the coronavirus on Saturday, and 1,050 deaths, the fifth consecutive day with more than 1,000 fatalities, the Health Ministry said.
More than 200,000 people have died of Covid-19 in Brazil.
Brazilian football has continued during the pandemic, although like most parts of the world, games are being played inside empty stadiums.
