They are top of the group with four points, and play their final game against Cameroon on Monday in the capital Brasilia.
The draw was their first in 17 games, going back to before a Confederations Cup triumph last year. Their 10-game winning run started last September.
The players acknowledged they need to up their game with the knockout stages not far away.
"We have to improve a few things, of course, but we do that (by) playing," said left back Marcelo. "Now we have a game against Cameroon to improve things."
Centre half David Luiz said the players were still adjusting to a more competitive level after the Confederations Cup and a year of friendlies. As host nation, Brazil qualified automatically for the 2014 World Cup.
"We know that we can get better, that we can grow, but we also know what we're up against," Luiz told reporters at Brazil's training camp outside Rio de Janeiro.
"When you compare the Confederations Cup with the World Cup it's not the same, all the teams are very prepared for the World Cup. The level today is very high."
Marcelo said Brazil's fine performance at the Confederations Cup, when they won all five games and handed world and European champions Spain their heaviest competitive defeat in almost 40 years, had enabled their opponents to prepare.
"Many teams have studied us so it's harder now," he said. "We know we have to do what Felipao (coach Luiz Felipe Scolari) tells us but that's the World Cup, each game is harder than the one before."
Cameroon are bottom of the group having lost both their games to Mexico and Croatia.
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