LONDON (AP) — Light flyweight Zou Shiming of China opened defense of his Beijing gold medal with a 14-11 victory over Yosbany Veitia of Cuba on Saturday in the Olympic boxing tournament.

Cuba's Roniel Iglesias upset top-seeded Brazilian light welterweight Everton Dos Santos, while top-seeded light heavyweight Julio La Cruz of Cuba trounced Jordan's Ihab Almatbouli.

Irish light flyweight Paddy Barnes easily advanced to a quarterfinal bout with India's Devendro Laishram, who posted a sensational 16-11 upset of fourth-seeded Serdamba Purevdorj of Mongolia, the silver medalist in Beijing.

India's veteran coach, Gurbankhsh Singh Sandhu, said his promising team must move on quickly from AIBA's decision to overturn the result of welterweight Krishan Vikas' foul-plagued fight against American Errol Spence on Friday night.

"We are disappointed, but a rule is a rule," Sandhu said. "I can't fight rules. I'm here to train the boxers, and they are here to perform."

Although two bout results have been overturned in this increasingly wacky tournament, the last of the elite boxers finally hit the ring Saturday for their opening bouts, including the top seeds at light flyweight, light welterweight and light heavyweight.

In a fight that might have matched the two best amateur light welterweights in the world, Iglesias got a sweet decision over Dos Santos, who upset him for the world championship a year ago. Iglesias, the 2009 world champion, took a narrow lead out of the first two rounds with superior speed and precision before holding off Dos Santos, the latest top seed to fall.

Zou is a three-time world champion who became a national hero by winning China's first boxing gold medal in its home Olympics four years ago, but his road to a repeat is likely to be much tougher.

The cagey veteran with a martial-arts background won last year's world title and returned to the Olympics as the top seed. Zou struggled at times while surviving an early test from Veitia, whose aggression and toughness nearly turned the result.

Cuba fared much better when Almatbouli, Jordan's first Olympic boxer, lost 25-8 to the top-seeded La Cruz, who toyed with his opponent. La Cruz even showed remarkable sportsmanship toward his overmatched foe, stooping to help Almbatbouli out of the corner after accidentally shoving him to the canvas out of a clinch.

The traditionally powerful Cuban team qualified eight boxers for London, hoping to build on its mixed results in Beijing. Stung by multiple defections after Athens, a new generation took over for Cuba and returned from China with an impressive eight medals — but no golds for the first time in any Olympics it entered since 1968.

Light heavyweight Yamaguchi Falcao of Brazil edged China's Meng Fanlong on countback after an outstanding fight that left both men embracing, and Russian light heavyweight Egor Mekhontcev picked apart Australia's Damien Hooper 19-11 in the final bout of the afternoon session.

Hooper came out in only his uniform after he had to make a round of apologies for wearing a T-shirt featuring the Aboriginal flag on the ring walk for his opening-round victory over Marcus Browne of the U.S. team. Hooper then didn't fight with the same reckless abandon he showed against Browne, with Mekhontcev significantly outworking Hooper while solving the Australian's unorthodox style, capped by a standing-eight count after a stiff left hand to Hooper's face with 1 minute left.