Italian defender Marco Materazzi has appeared before a disciplinary committee in Zurich at the headquarters of football's world governing body, FIFA.
FIFA wants to find out what he did to provoke French midfielder Zinedine Zidane to head-butt him during Italy's World Cup title victory over France last Sunday in Berlin.
A FIFA spokesman refused to provide any details of the meeting. Materazzi is being investigated based on statements by Zidane, who was sent off for ramming his head into the defender's chest during extra time in the match.
Zidane said on French television Wednesday night that Materazzi insulted his mother and sister. Materazzi has admitted insulting Zidane, but denied verbally attacking Zidane's mother.
Zidane is scheduled to attend a FIFA hearing next Thursday to explain his actions. A decision is expected later that day.
FIFA has declined to comment on possible punishments for either individuals or teams.