Messi began playing football at a young age and his potential was quickly identified by Barcelona. He left Rosario-based Newell's Old Boys's youth team in 2000 and moved with his family to Europe, as Barcelona offered treatment for his growth hormone deficiency. Making his debut in the 2004--05 season, he broke his team record for the youngest footballer to score a league goal. Major honours soon followed as Barcelona won La Liga in Messi's debut season, and won a double of the league and Champions League in 2006. His breakthrough season was in the 2006--07 season; he became a first team regular, scoring a hat-trick in El Clásico and finishing with 14 goals in 26 league games. Messi then had the most successful season of his playing career, the 2008--09 season, in which he scored 38 goals to play an integral part in a treble-winning campaign. This record breaking season was then eclipsed in the following 2009--10 campaign, where Messi scored 47 goals in all competitions, equalling Ronaldo's record total for Barcelona.
Messi was the top scorer of the 2005 FIFA World Youth Championship with six goals, including two in the final game. Shortly thereafter, he became an established member of Argentina's senior international team. In 2006, he became the youngest Argentine to play in the FIFA World Cup and he won a runners-up medal at the Copa América tournament the following year. In 2008, in Beijing, he won his first international honour, an Olympic gold medal, with the Argentina Olympic football team.