A graduate of the world-famous Ajax youth system, John O'Brien was one of the stars of the USA's march to the quarter-finals of the 2002 World Cup. He showcased the full range of his incisive passing at Japan/Korea 2002 and looked set to go on to establish himself as one of the world's best midfielders. However, his appearances for club and country have been severely limited by injuries over the past four years. After being released by Ajax he joined ADO Den Haag for the 2005-06 campaign, but a groin injury ensured he made little impact at the Zuiderpark and he was allowed to sign for MLS side Chivas USA in April.