Brazil coach Dunga admitted his side had shown "nervousness and anxiety" in their World Cup opener against North Korea at Ellis Park before running out 2-1 winners.
Maicon made the breakthrough for the five-time world champions with a shot from an acute angle and Elano added a superb second when he sidefooted home a brilliant through-ball from Robinho.
"The first match is always very tiring," said Dunga. "There is a lot of nervousness and anxiety after a lot of training sessions. All of us want to score and not concede any goals."
He added: "I'm not entirely happy but this is common in football. In the second half we changed our rhythm a bit. At first we were passing side to side but in the second half we improved a lot.
"The spirit of this team is noteworthy and this team wants to go forward."
Dunga admitted his side found it hard to break down a team who, at 0-0, were content to pack the defence and try to keep Brazil out.
"When we come across a team that is also offensive it creates the necessary space but it is very difficult against some teams to develop a counter-attack," he said. "North Korea passed extremely well and defended extremely well but nevertheless Brazil were able to create a number of opportunities."
North Korea coach Kim Jong-hun was proud of his men despite the defeat, with Ji Yun-nam's late goal providing cause for celebration and hope for things to come against Ivory Coast and Portugal.
Kim said: "The Brazilian team is a very strong team and, although we were unable to win the game, I believe our players fought very well.
"For the first half our players really carried out our plan for the Brazilian team - when they were attacking from the sides or the wings, or at individual plays. We managed to fend them off. We were very well prepared to fight against any of their tactics and when we intercepted the ball we passed very quickly."