Argentina will not defend Olympic crown
Brazil, who need the Olympic title to complete the full array of major football prizes, won their third successive South American under-20 title in Peru with a 6-0 victory over Uruguay in their final match.
Uruguay will return to the Olympic tournament for the first time in 84 years having won the title in Paris in 1924 and Amsterdam in 1928 in their only two previous appearances.
Argentina, inspired by Barcelona's Lionel Messi, won their second successive Olympic gold in Beijing in 2008, but finished third in the South American round-robin competition.
Brazil teenager Neymar, who has already appeared for the senior side, scored nine goals in the competition.
The top four teams in the competition, Brazil, Uruguay, Argentina and Ecuador all qualified for the under-20 World Cup, which will be hosted by Colombia in July.