What FIFA World Cup did the referee of the 28 May 2011 football match at Wembley Stadium participate in? 
Viktor Kassai: Viktor Kassai ("Kassai Viktor", : ; born 10 September 1975) is a Hungarian football referee. Viktor Kassai:  He participated in the 2010 FIFA World Cup and refereed the 2011 UEFA Champions League Final. 2011 UEFA Champions League Final: The 2011 UEFA Champions League Final was a football match played on 28 May 2011 at Wembley Stadium in London that decided the winner of the 2010–11 season of the UEFA Champions League.
2010 FIFA World Cup