Alexandre Pato scored the first goal in the sixth minute, before a packed-out crowd that included Vietnam president Nguyen Minh Triet in Hanoi's 40,000-seater My Dinh stadium. However, the AC Milan forward's second attempt to score in the 46th minute was warded off by Vietnam's goalkeeper, the Brazil-born Fabio Dos Santos, who became a naturalised Vietnamese citizen in December.
Vietnam nearly equalised just after half-time, when striker Nguyen Viet Thang took a shot which goalkeeper Diego Alves deflected away to safety, and again when Nguyen Minh Duc hit the goal post with a long-range shot.
In the 81st minute, Thiago Neves, voted the best player in the Brasileirão last year, scored Brazil's second goal. Two minutes later, Jo, who recently inked a four-year deal with English Premier League club Manchester City, found the net again for the Seleção but the goal was disallowed.
"Tonight the Vietnamese team played a very good game. ," said Ronaldinho afterwards.
Brazilian coach Dunga said: "I'm happy with the match although we had little training. We would like to thank Vietnamese fans and the hosts for giving us a warm welcome and good preparation."
Despite the loss, for many Vietnamese fans just having the samba kings on their home turf came close to a religious experience. "Having the Brazilian players in Vietnam is a once-in-a-lifetime event," enthused Nguyen Bich Lien, 50, from Ho Chi Minh city.
"It's a great opportunity to see Ronaldinho, Pato and Anderson," agreed Tran Hung Dung, 28, wearing a yellow Brazil shirt and a Vietnamese conical hat. "It's unbelievable to see them playing football in Vietnam. The Vietnamese are like the Brazilians in their love for soccer."
Pato said at a post-match press conference: "I'm very surprised about the warm welcome and the enthusiasm from the Vietnamese fans for soccer. I will have a lot of things to tell my friends back home."
The Brazilian Olympic team flew in from another exhibition match in Singapore this week to play Vietnam. They will next travel to Beijing, where the Men's Olympic Football Tournament will begin on 6 August.