In a live interview to be broadcast on Canal Plus at 8.00pm (1700 BST), Zidane is expected to explain the nature of the slur hurled at him before Sunday's incident by Marco Materazzi, the Italy defender.

Materazzi, who was knocked to the ground by the extra-time butt to the chest, has acknowledged that he insulted Zidane, but denied that he called him a terrorist or impugned his mother. "It was an insult of the kind you will hear dozens of times and that just slips out on the ground," Materazzi told an Italian newspaper. However Jessica Rees, a lip-reader consulted by The Times, concluded that Materazzi called Zidane the "son of a terrorist whore."

Fifa has launched an investigation into the incident, which resulted in Zidane's sending-off shortly before France's 5-3 defeat on penalties. Sepp Blatter, the Fifa president, warned that he could strip Zidane of his Golden Shoe title - awarded to the World Cup's best player after the final - if the disciplinary committee finds against him.

Zidane also faces suspension from future matches, but this will have little impact as he had already announced his retirement from all professional football.

Despite feverish speculation over the reasons for his gesture, France's favourite footballing hero has received overwhelming support from the public - with 61 per cent telling a French national newspaper that they forgive him and 52 per cent that they understand his behaviour.

Top politicians have also indicated that the incident must not be allowed to overshadow Zidane's status as role-model and world-class athlete with President Chirac hailing him as a "virtuoso, a genius of world football."

Legal challenge to World Cup result

A French lawyer plans to mount a legal challenge to the World Cup final result to establish whether the expulsion of Zinedine Zidane was within the rules.

Mehana Mouhou said he intended to ask a Paris court to question the fourth official to ascertain whether he had illegally used videotape to check what had happened.

"If a judge determines that illegal methods were used, the proper consequences must be drawn," he said. "That means that Zidane should never have been sent off and it would be impossible to predict what the match result would have been and it should be replayed."

Mouhou said he was acting on behalf of "several football clubs."