The United States suffered their worst day of the Athens Olympics on Friday when a tearful Marion Jones flopped; their basketball "Dream Team" were humiliated and they captured only one of the 20 golds on offer.

But China, who had never won an Olympic gold in athletics, had a night to remember with Liu Xiang winning the men's 110 metres hurdles in a world record equalling 12.91 seconds.

"My victory has proved that athletes with yellow skin can run as fast as those with black and white skin," said Liu, 21.

"This is a miracle, but I believe a lot more miracles will take place in China," he said, as a new generation of his compatriots signalled they will be a force to be reckoned with on the track when Beijing hosts the next Olympics in 2008.

Xing Huina beat the Ethiopians at their own game to win the women's 10,000 in one of the biggest upsets of the athletics.

Only a giant leap by pole vaulter Tim Mack ensured the day did not end without the "Star Spangled Banner" being played at a medal ceremony and saved the Americans the ignominy of no golds on Day 14 of the Games.

Marion Jones, darling of the track in Sydney in 2000 with three gold medals and two bronzes, capped her worst year by finishing fifth in the long jump and was then embarrassingly, at the centre of a botched relay hand over.

TEARFUL JONES

"I exceeded my wildest dreams in a negative sense. We were looking for great things to happen, they didn't happen today," said Jones, tears in her eyes.

"It's extremely disappointing, words can't put it into perspective."

Despite screaming "Wait, wait, stop" to the third runner on the team as she completed the second leg, Jones could not reach Lauryn Williams with the baton in the final of the 4x100 metres.

When she finally made contact on the fourth attempt it was too late for the Americans and Williams did not even attempt to catch up with the Jamaican runners who went on to win.

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Earlier this year, the U.S. Anti-Doping Agency investigated Jones when the BALCO laboratory in California was raided after the discovery of the new steroid THG (tetrahydrogestrinone).

Capping a nightmare Games for a basketball team laden with multi-million dollar professionals, the Americans were denied an Olympic gold medal for the first time since 1992 when NBA players started competing.

Once glamorous superstars of the basketball tournament, the United States were beaten 89-81 by Argentina in the semi-finals.

"It's important for us to come out tomorrow and play to make the people back home proud of us," U.S. guard Allen Iverson said of his team's bronze medal match on Saturday.

Underlining the shock win by Xing, Ethiopia's Ejegayehu Dibaba was convinced she had won the women's 10,000 metres until an official explained she had taken only the silver.

Dibaba was overtaken by the previously unknown 20-year-old Xing in the last 100 metres of the race but thought she was a lapped runner.

An official asked her: "You are the one who came second, right?" Dibaba replied: "No, first."

Dibaba, looking stunned, still refused to believe it until the truth gradually dawned.

"I didn't see where the Chinese girl came from," she said.

RADCLIFFE QUITS

Briton Paula Radcliffe gave up the race, quitting for the second time in a week after she stopped running the marathon.

China, who won 28 gold medals in Sydney four years ago, now have 27 golds in Athens, just two behind the United States and 10 ahead of Russia and Australia.

With two days of the Games left to go, police fired teargas at hundreds of demonstrators trying to reach the U.S. embassy to protest against a visit by U.S. Secretary of State Colin Powell.

One protester called the visit political provocation, saying "94 percent of Greeks were against the war in Iraq".

The U.S. Olympic Committee accused the International Gymnastics Federation of putting "outrageous and improper" pressure on Paul Hamm to give up his gold medal to South Korean Yang Tae-young, victim of a judging error.

There was no apparent end to doping woes that struck on the eve of the Games when two Greek sprinters missed drugs tests.

The International Olympic Committee set a 1400 GMT deadline for Hungarian hammer gold medallist Adrian Annus to submit a fresh urine sample or lose his gold medal but said late on Friday they had still not heard whether he had complied.

Another Hungarian athlete, silver medallist weightlifter Ferenc Gyurkovics, gave a drugs positive sample.

Iraqi dreams of winning only their second Olympic medal were shattered when Italy beat them 1-0 in a men's soccer bronze match overshadowed by the killing of an Italian hostage in Iraq.

Italy wore black armbands in honour of journalist Enzo Baldoni, and Iraqi captain Abdul Wahab presented his counterpart Andrea Pirlo with a bouquet of flowers.