Mark Shield was only 28 when he saw on the internet that he was chosen by the FIFA for the World Cup finals in 2002. Since his own country Australia was not taking part he was even a possible candidate for more than one match, but that didn't happen.
The Australian number one referee started as a football player, but at the age of twelve when everybody realized he wasn't good enough, they asked him to pick up a flag and run the line. It didn't take him long to decide that refereeing was much more enjoyable and that he was good at it.
Elite referee Mark Shield officiated one match (Tunesia-Belgium) in the first round of the 2002 World Cup finals and two matches (Iran-Angola, Tunesia-Saoudi Arabia) in the first round of the 2006 World Cup finals. For the latter tournament he took charge of two qualifiers in Europe, only one of two referees not from Europe to do so.
Shield was the youngest participating referee at the World Cup finals in 2002 and 2006.
In november 2006 Shield was appointed to be in charge of the AFC Champions League final between Al Karama from Syria and Jeonbuk Hyundai Motors from South Korea. His most important match is probably the 2007Asia Cup final between Iraq and Saoudi Arabia (1-0).
Shield was AFC referee of the year 2007.
Mark Shield is on the 54 member shortlist of candidates for the 2010 World Cup in South Africa, but that turned out to be wishful thinking (on the part of FIFA): in September 2008 Shield announced he was going to quit at the end of the year For reasons of family and business.