The brand-new stadium built at a cost of 592 million reais ($296.58 million) in the northern city of Salvador will be one of six used for the June 15-30 Confederations Cup, an eight-nation dress rehearsal for the World Cup.
Delays forced world football's governing body FIFA to extend the deadline for the first batch of stadiums until April 15.
Preparations for the tournament, and the Olympic Games in 2016, are behind schedule, raising doubts about the country's ability to organise the two global events that will draw hundreds of thousands of visitors.
"We are an unbeatable country. We will show that Brazil can deliver great quality to the Confederations Cup, the World Cup and the Olympics," Rousseff said at the opening of the Salvador stadium.
To standardise names and make it easier for foreign fans buying tickets, FIFA will shorten its name to National Stadium Brasilia, dropping the name of the football great Mane Garrincha, star of Brazil's 1962 World Cup victory, a city official said.
The last stadium to be ready will be the Maracana in Rio de Janeiro, once the world's largest but now overhauled to fit a reduced capacity of 78,639 spectators. It is due to be delivered on April 27.
