Ronaldinho will captain Brazil at the Olympic Games next month.
The 28-year-old, who recently joined AC Milan from Barcelona, was handed the skipper's armband by coach Dunga as the South Americans aim to secure gold in Beijing.
'This is a great responsibility, which motivates me a lot as it is also proof of confidence,' the playmaker said. 'I am very happy.'
Dunga also admitted he is delighted with the way his squad have gelled as they prepare to face New Zealand, Belgium and hosts China in Group C.
'The players are happy because the environment is excellent,' said the coach. 'That is one of the steps to achieving our objective in football. It is not enough just to have a great team.
'The only way to win a title is having a real group and that is what is going on here.'
The Brazilians will play a warm-up match against a Singapore select XI on Monday before travelling to Hanoi for a friendly with Vietnam four days later.