After receiving only the third red card of his career against Ivory Coast, the usually placid Kaka, considered a role model in Brazil, was booked for a trip on Arturo Vidal in the first half of Monday's second round game.
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"It's a problem, I don't want Kaka to get suspended again," Dunga told reporters.
"The technically gifted players are getting punished and the ones who kick and commit fouls are being let off.
"We've got three players with injuries and we can't afford to lose them at this stage."
Dunga added that Brazil still had to improve despite giving their best performance of the competition so far to reach the quarter-finals.
"We have to improve in all areas of our play," he said.
"It was a very nice game and Chile played exceptionally well with a lot of possession, they passed the ball well, but Brazil were able to maintain a balance and stay in control.
"In these World Cup games we have to go forward and play open football, that's what everyone wants to see."
He also denied that Brazil's tactics were rigid.
"I've always said that my players have the liberty to play."
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