Zinedine Zidane is facing a FIFA probe after the world governing body launched an investigation into his controversial sending-off in the World Cup final.

The Frenchman was shown the red card after head-butting Italy's Marco Materazzi in extra time of Sunday's game in Berlin.

Zidane reacted after being insulted by Materazzi but was only dismissed after the intervention of the fourth official, as referee Horacio Elizondo did not see the incident.

Several reports had suggested that officials used video evidence before making the decision, which is against regulations, but have FIFA denied this.

A statement read: "The incident was directly observed by fourth official Luis Medina Cantalejo from his position at the pitchside, who informed the referee and his assistants through the communications system."

Zidane's sending-off proved pivotal in the match as Italy, despite being under pressure for much of extra time, went on to win on penalties.

Theories have abounded as to what Materazzi might have said to provoke such a response and the former Everton defender concedes he did make an offensive remark.

Materazzi, 32, told Gazzetta dello Sport: "I held his shirt for a few seconds only, then he turned to me and talked to me, jeering.

"He looked at me with a huge arrogance and said, 'If you really want my shirt I'll give it to you afterwards'. I replied with an insult, that's true."

Materazzi has not elaborated on what he did say, but one report suggested he responded to this with: 'I'd rather take the shirt off your wife'.

He has denied, however, some of the more vile insults being reported which refer to Zidane's wife or sister or calling him a terrorist.

"It was one of those insults you're told dozens of times and that you often let fall on a pitch," Materazzi said.

"I did not call him a terrorist. I am not a cultured person and I don't even know what as Islamist terrorist is."

He added: "For me the mother is sacred, you know that."

Any comments made will be a key element in FIFA's investigation.

The red card brought an undistinguished end to Zidane's glittering career in his final professional match, but he has received much support in France even though his actions may have contributed to the defeat.

The 34-year-old also received the Golden Ball award for the best player in the tournament.

He is yet to speak on the incident himself but his agent yesterday claimed the reaction was due to a "very serious" comment.