The Brazilian government on Tuesday sanctioned the partial return of fans to football stadiums.
"It is important to stress that the reopening should be up to 30% of capacity of stadiums," Brazil's Health Ministry said in a short statement, adding that the percentage can increase later if required.
The decision would allow for crowds of around 25,000 in Rio's Maracana stadium and came after the Brazilian Football Confederation asked health officials to rule on their proposal to get fans back into grounds that have been closed since March when football shut down due to the spread of the Covid-19 pandemic.
Individual cities can override the decision, with Belo Horizonte saying it will veto the return of fans, according to Brazilian media reports.
Hundreds of people are still dying each day from Covid-19 in Brazil, one of the world's most badly-affected nations, and the decision comes the same day that the British government shelved plans to allow fans to return to watch live sport.
Professional matches kicked off again in June in Rio de Janeiro and in Sao Paulo state, Brazil's most populous, in July.
Clubs, however, are struggling to keep their players virus-free.
Brazilian champions Flamengo, for example, were due to play a Copa Libertadores tie in Ecuador on Tuesday but seven players and two staff tested positive for Covid-19 before the match.
Several other clubs have reported similar problems, with one Brazilian league game last month cancelled just minutes before kickoff after members of one side tested positive.
More than 136,000 people have died from Covid-19 in Brazil, the second highest death toll in the world after the United States.