Although neither player has yet revealed the nature of their disagreement, Fantastico, a programme on Globo, employed lip-reading experts who said footage of the incident showed the Italian twice insulted Zidane's sister.
The programme claimed Materazzi made the same comment twice before then using a "coarse word" aimed at the French player.
There have also been reports Materazzi had called him a "terrorist" or suggested he did not have the right to play for France - both insults based on French-born Zidane's Algerian heritage.
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Zidane's agent Alain Migliaccio confirmed to the BBC on Monday that it had been verbal rather than physical abuse from the Italian defender which had triggered his violent reaction. "He told me Materazzi said something very serious to him but he wouldn't tell me what," Migliaccio said.
"Zinedine didn't want to talk about it but he will talk about it in the next couple of days.
"He is a man who normally lets things wash over him but on Sunday night something exploded inside him. He was very disappointed and sad. He didn't want it to end this way."
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