LONDON -- Mongolia's light welterweight pulled off one of the biggest upsets of the Olympic boxing tournament Wednesday night, stunning second-seeded Tom Stalker of Britain and his home crowd with a 23-22 victory.
Britain immediately protested Stalker's narrow loss to Munkh-Erdene Uranchimeg, but it was rejected.
Yamaguchi Falcao of Brazil also upset top-seeded Cuban light heavyweight Julio La Cruz 18-15 in an eventful final day of quarterfinal bouts.
The evening ended with Algerian light heavyweight Abdelhafid Benchabla's 19-17 loss to Ukraine's Oleksandr Gvozdyk, which left a small group of angry Algerian fans running up and down the stairs in the stands and shouting toward the ring. One fan hurled a desk lamp from the press tribune onto the arena floor. The lamp broke but didn't hit anyone, and no fans were detained by security.
Algeria protested Benchabla's loss, which was affected by a last-minute holding penalty that resulted in the decisive margin of victory. But it was also rejected by amateur boxing's governing body.
Chinese light flyweight Zou Shiming barely avoided an upset as well, holding off Kazakhstan's Birzhan Zhakypov 13-10 to clinch his third Olympic medal. Zou's next bout is against Ireland's charismatic Paddy Barnes in a tantalizing rematch of Zou's 15-0 victory in Beijing.
"My plan for my next bout is to score one point," said Barnes, perhaps the biggest character in the tournament. "That's my Olympic goal. I intend to score a point against him. You can tell him I said that, too."
The field is fully set for the 20 semifinal bouts on Friday after the only off day of the men's tournament on Thursday.
Ukraine will lead the men's tournament with five medals after Gvozdyk and light welterweight Denys Berinchyk clinched with victories Thursday night, while Britain and traditional powers Russia and Cuba will go home with four apiece. Zou will win China's only medal for a team that captured four in Beijing.
Uranchimeg clinched his first Olympic medal in his third trip to the games with a gritty effort against Stalker, the British team captain and a crowd favorite in the ExCel arena. Those fans were largely shouted down by a small band of Mongolian fans as Stalker struggled, lost and bolted from the ring after the decision.
"He's looked forward to these games for so long," British coach Dave Alloway said. "To lose by one point in the last bout before a medal, that's probably the hardest thing that could happen. I'm sure he'll be back in tomorrow, cheering on this team. He's one in a million."
Britain will finish its home Olympics with a remarkable five boxing medals, but two of its biggest stars lost in tough fashion: Two days after top-seeded middleweight Savannah Marshall was knocked out of the games in her first fight, Stalker couldn't rally past Uranchimeg, who smiled broadly as he left the ring.
La Cruz took his loss with much more aplomb than Stalker, with the Cuban world champion smiling and bowing to the crowd after another remarkably even fight. Falcao's brother, Esquiva, also will win a medal after reaching the middleweight semifinals.
The Falcao brothers' efforts are auspicious for Brazil's own boxing hopes at its home Olympics in four years. Brazil had won just one boxing medal in its history before claiming two more with a much-improved team in London.
Zou was the first boxing medalist in Chinese history at the 2004 Athens Games, and became the first gold medalist under enormous home pressure in 2008 in Beijing. He won another world title last year, but in London, he hasn't been the near-unhittable dynamo who dominated the field at the 2008 Games.
Zhakypov did plenty of damage to Zou, whose martial arts-based style barely kept him in the tournament.
"I believe the referees were helping him a lot," Zhakypov said through a translator. "I do not agree with the decision."
Barnes beat India's Devendro Laishram 23-18 to clinch his second Olympic medal. With that Beijing blowout and another loss at last year's world championships in his mind, Barnes has ample motivation to pay back Zou after already clinching the Irish team's third medal.
"I slacked off a little in the third round and got hit with a couple of shots," Barnes said. "It's OK. I'll learn from it and move on from here. I don't need rest. After this weekend, I'll have 40 days of rest."
Barnes had little trouble scoring against Laishram before handling his post-fight interviews with his Twitter handle -- (at) paddyb-ireland -- written on the tape on his water bottle, part of his quest for more sponsorship.
"It's low at the moment, but (British boy band) One Direction tweeted me yesterday, so that will give me a few followers," Barnes said.
With Laishram's loss, India headed home from London with only Mary Kom's bronze medal to show for an eight-member team. India is a rising power in amateur boxing, but it took a number of disheartening defeats in London.
Russia's David Ayrapetyan and Thailand's Kaeo Pongprayoon clinched medals on the other half of the light flyweight bracket.
Roniel Iglesias also clinched his second Olympic medal, with the graceful Cuban light welterweight handling Uzbekistan's Uktamjon Rahmonov 21-15. Iglesias' semifinal is against Italy's Vincenzo Mangiacapre, who rallied past Kazakhstan's Daniyar Yeleussinov 16-12.
Uranchimeg is in the other light welterweight semifinal against Berinchyk.