Cuba's Roniel Iglesias Sotolongo got the better of Everton dos Santos Lopes again, ousting the top-seeded Brazilian from the men's light welterweight draw.
Iglesias Sotolongo won a bronze medal four years ago in Beijing, and beat dos Santos Lopes in last year's Pan American Games.
Saturday, he toppled the Brazilian by an 18-15 score to move into the quarterfinals. Also advancing in the draw were Ukrainian Denys Berinchyk and Great Britain's Thomas Stalker, the No. 2 and 3 seeds, respectively.
The top seed in the men's light flyweight draw, China's Zou Shiming, advanced, but No. 2 seed Shin Jonghun of South Korea fell to Bulgarian Aleksandar Aleksandrov.
In men's light heavyweight action, the top four seeds -- Cuban Julio la Cruz Peraza, Algerian Abdelhafid Benchabla, Kazakhstan's Adilbek Niyazymbetov and Egor Mekhontcev -- won to get to the quarters.