The Canarinha, winners of their opening two games, are in first place and two points clear of second-top Portugal.

Brazil have had so much success over the years, draws are never good enough for their fans and they certainly do not accept defeats.

"Brazil has to win, otherwise I am going to have tremendous problems," said Dunga.

"We have no other option, we play to win, we must play to win.

"The important thing is we play the best we can."

Dunga has reminded his players he will not tolerate indiscipline from now on.

Brazil will be without star player Kaka for tomorrow's match as he serves a one-match ban after being sent off for a double booking against the Ivory Coast.

"Since the qualifying matches, we have to start our games with 11 players and finish them with 11 players," he said.

"Having said that I would like to reiterate Kaka did not show any kind of nervousness against the Ivory Coast.

"I think he played a balanced game and he got his first yellow card after being fouled and then he got a second card even though Kaka did not provoke his rival."

Dunga believes Kaka's absence will not hinder his side.

"We all know Kaka is a unique player," he said.

"But Julio Baptista has already played in the Copa America with us and he adapts well to going forward.

"Baptista is very powerful and is a good shooter from outside.

"But we have to play as a collective."

One player who is likely to sit out the encounter against Portugal is Galatasaray midfielder Elano, who sustained a calf injury in Brazil's second victory shortly after scoring.

"He might now play tomorrow," said Dunga. "But we will wait and see what happens."

Portugal head into the match in buoyant mood after thrashing North Korea 7-0 in their last game.

Dunga expects the Portuguese to show the same attacking flair as they did against the Asian side.

"Portugal is going to have to attack in order to secure points," he said.

"I believe Portugal are going to play as they have played up to now."

One player that stands out in the Portuguese side is Real Madrid star Cristiano Ronaldo.

"We are not going to mark a specific player," said Dunga. "We are going to mark all of the Portuguese players."

The last time both sides met back in 2008, Brazil humiliated Portugal 6-2 in a friendly in Brasilia.

"The past is the past," said Dunga. "This is a new game and I think it's going to be a great encounter for all football lovers.

"It's going to be an interesting game as Brazil versus Portugal always is.

"Our style of football is similar.

"With both sides, when they have possession, they go out to score."

Dunga is nevertheless confident his side will come out triumphant as long as they play like only Brazil knows how.

"Whenever we play organised and attacking football, we always do well," he said. "I think we have a balanced team and that is the aim of any side, to play balanced football."