Maracana needs a new roof before the 2014 World Cup, possibly delaying the stadium's readiness by a year to 2013.
The stadium was expected to be ready by the end of 2012, but Brazilian football federation president Ricardo Teixeira told local channel SporTV that it possibly won't be in shape before 2013. He said the goal remains to have Maracana prepared for that year's Confederations Cup.
Maracana will host the World Cup final, just as it did when Brazil organized the tournament for the only other time in 1950.
The stadium hasn't been used since last September because of the renovations.
Teixeira said late Wednesday that a new roof was necessary because of ''unexpected'' problems with the current roof.
In January, Rio de Janeiro city officials found deterioration in some materials used in the roof's structure, but at the time there wasn't enough evidence to confirm it was compromised. The full extent of the problem was discovered after a study by the city department in charge of revitalizing the venue.
According to Teixeira, engineers said it was easier to build a new roof than to fix it. The initial project included keeping the original roof.
It wasn't announced how the changes would affect the renovation cost, which originally was estimated at about $430 million. Some local media reports said it could surpass $600 million now.
Maracana underwent extensive renovation in 2005 to make it ready for the 2007 Pan American Games hosted by Rio de Janeiro.
Teixeira's announcement of problems with Maracana's roof came just days after FIFA President Sepp Blatter criticized Brazil's preparations for the 2014 World Cup. He urged officials to speed up construction work for the monthlong tournament, including at stadiums.
Teixeira denounced Blatter's criticism on Wednesday, but acknowledged that some host cities were facing difficulties.
''We have problems in Sao Paulo and Natal because the stadiums there haven't started being built yet,'' Teixeira said.
The stadium in Sao Paulo is expected to host the opening match.
Teixeira also said the lack of upgrades in the country's outdated airports remains a big concern, but added the government was aware of the difficulties and was working to solve the problems.