Great Britain's Freddie Evans won his opening bout in the men's welterweight competition Sunday, as he began his quest for an Olympic medal.
Evans outpointed his opponent, Algerian Ilyas Abbadi, by an 18-10 margin and moved on to face fourth-seeded Egidijus Kavaliauskas of Lithuania in the 69- kilogram category.
The Welsh Evans burst upon the boxing scene last year, when he won the welterweight gold at the European Championships.
American Errol Spence and Australian Cameron Hammond, ranked fifth in the world, were among the other welterweight winners.
The lightweight (60kg) competition also began Sunday, and fifth-seeded Gani Zhailauov advanced in a close bout against Thailand's Saylom Ardee. They were tied on points, 12-12, after three rounds and the Kazakh won on countback.
Zhailauov won bronze at the 2011 world championships.
American Jose Ramirez and Turkey's Fatih Keles, the No. 6 seed, also won in early-round lightweight action.
Boxing continues Monday, when the flyweight (52kg) and light heavyweight (81kg) competitions begin.