At international level, Agüero represented the Argentina under-20 team at the FIFA U-20 World Cup in 2005 and in 2007, winning both tournaments. Agüero played at the 2008 Beijing Olympics, he scored two goals in the 3–0 semi-final win against Brazil as Argentina went on to win the gold medal. Agüero was selected to represent Argentina in the 2010 FIFA World Cup and the 2011 Copa América.
In 2006, Agüero moved to Europe to play for La Liga side Atlético Madrid for a fee of €23 million from Independiente. He made a name for himself, attracting attention from Europe's top clubs by scoring 101 goals in 234 appearances while winning the UEFA Europa League and the UEFA Super Cup in 2010. Agüero moved to Premier League club Manchester City in July 2011 for an undisclosed fee thought to be in the region of £35 million. On the last day of his début season with the club, Agüero scored a 94th-minute winner against Queen's Park Rangers that earned Manchester City their first league title in 44 years. In 2012, he won Manchester City's player of the year as voted for by the fans.