Assistant referee (association football)
The fifth official used to be a backup for assistant referees in football matches, ready to step in if an assistant got injured. During the 2006 World Cup, FIFA had five officials for matches. The fifth official helped the fourth official with various tasks and could replace another official if needed, mainly due to injuries. The fifth official could watch the match on TV but couldn't tell the on-field referees about any missed incidents. After the 2006 FIFA World Cup Final, Italy's coach claimed the referee received advice from the fourth and fifth officials watching video footage, but FIFA denied this.