Brazil coach Luiz Felipe Scolari admits his players are becoming "more afraid" as they prepare to face Chile in the first of the World Cup knockout ties.
"It is normal for us to be anxious, especially now in the knockout stage where we cannot lose," Scolari said.
"We become more afraid, more nervous. It is normal. Not because it is in Brazil, but because it is a World Cup."
The hosts won two and drew one of their group games to qualify comfortably for the last 16, with star man Neymar scoring four goals.
But Chile were also impressive in wins over Australia and Spain to book their passage from Group B.
Scolari, who led Brazil to World Cup success in 2002, said shortly after the draw was made last December that Chile would be one of the teams he would least like to face.
"I'd rather play any of the others," said the former Chelsea coach. "They're a pain to play against."
Meanwhile, Brazil said comments from Chile forward Alex Sanchez about the match officials were disrespectful.
Barcelona player Sanchez said: "The only thing I fear is the refereeing."
When Scolari was asked to respond, press officer Rodrigo Paiva intervened.
"We are going to talk about this only once," he said. "The press and Chile have insisted on this issue. This is immature in this moment in football.
"This kind of pressure is even ridiculous."
Webb officiated the 2010 World Cup final between Spain and Netherlands, and took charge of Brazil's win over Chile in the last 16 at the same tournament.
Paiva added: "Talking about this is not just a lack of respect towards Fifa, or the referee alone, or the Brazilian team, or to the people who work here in a very serious manner with 100 years of football history, a winning history.
"We think this is a lack of respect for the Brazilian people. Brazil does not need the help of the referee to win a match."
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