After 2005, it was held every four years, in the year prior to each World Cup in the host country of the forthcoming World Cup (the 2001 edition was hosted in South Korea and Japan, before the quadrennial pattern was established). Considered a dress-rehearsal for the World Cup it precedes, it used around half of the stadiums intended for use at the following year's competition and gave the host nation, which qualified for that tournament automatically, experience at a high level of competition during two years of otherwise friendlies. At the same time, participation was made optional for the South American and European champions.