China picked up four gold medals in Day Two's action to take its total to six and top the medals table. South Korea and the United States are in second and third place respectively.

Watched and cheered by US President George W. Bush, Phelps sent thousands of spectators at the Water Cube to raptures when he touched home in a time of four minutes 3.84 seconds, slicing 1.41 seconds off his own world record set in June.

"I was in the ready room. I didn't feel so good, I got these cold chills," said Phelps. "Afterwards, I looked up and saw President Bush giving me the thumbs up and holding up the American flag. That was pretty cool."

In the pool, another world record fell with Australia's Stephanie Rice chopping nearly two seconds off the world best in the women's 400m individual medley. Rice clocked 4:29.45 to take her first major title and Kirsty Coventry of Zimbabwe grabbed silver.

Park Tae-hwan notched South Korea's first Olympic gold in swimming when he cruised to victory in the men's 400m individual freestyle final. But Zhang Lin's performance was also notable as he finished second behind Park to become China's first male Olympic medalist in swimming.

Chinese male swimmers' previous best performance at the Olympic Games was a fourth-place finish by Jiang Chengji at the Atlanta Olympics in 1996.

"I trailed Park by less than one second, but I've tried my best," said Zhang. "I did not think I would get a silver medal."

There was more good news for the hosts Sunday from the shooting hall. Guo Wenjun scored 492.3 points to claim the women's 10m air pistol title, one day after compatriot Pang Wei won the men's air pistol.

The all-conquering Chinese diving squad started its bid for a clean sweep of eight golds with Guo Jingjing, dubbed as the "Diving Queen", and Wu Minxia successfully defending their synchronized 3-meter springboard title.

"I am satisfied with my performance today and we are both very happy, because we are on home soil in China," said the 27-year-old Guo, who has announced she would retire after the Beijing Games.

China's Xian Dongmei, who had a baby daughter 18 months ago, made a successful comeback when she outclassed a handful of big names to retain her 52kg judo crown. The 33-year-old veteran knocked out European champion Ana Carrascosa of Spain and 2007 world championships finalist Telma Monteiro of Portugal en route to victory.

"Thank my husband for supporting me to return to the sport," Xian said emotionally after the final.

"This is my last Olympics. I will make it up to my family, especially my daughter," she added.

Long Qingquan capped a golden day for China when the 17-year-old weightlifter won the men's 56kg class, lifting 132kg in the snatch and 160kg in the clean and jerk. Both the snatch and the total result were junior world records.

But to the disappointment of millions of Chinese soccer fans, their national men's team lost 2-0 to Belgium and ended the match with nine man.

With Brazil already through from Group C after two wins out of two, China must beat the South American side in their final game to keep alive hope of reaching the quarterfinals.

In a much-hyped basketball game, the NBA star-studded US team was little tested by the Chinese team which boasts Yao Ming. The Americans won by 101-70.

In fencing, Matteo Tagliario of Italy downed Fabrice Jeannet of France 15-9 to claim the men's epee gold.

In archery, South Korea underlined its status of powerhouse when they beat China in a repeat of the Athens final to win a sixth straight Olympic gold.

The Czech Republic won its second gold with David Kostelecky in the men's shooting trap.

There were first golds for Japan with Masato Uchishiba in judo men's 66kg class and for Britain with Nicole Cooke in the cycling women's road race and for Thailand with Prapawadee Jaroenrattanatarakoonon in the women's 53kg category.

Greek sprinter Katerina Thanou was ruled ineligible for competing at the Beijing Olympics for her role in the "scandalous saga" that tainted the Athens Games.

The International Olympic Committee executive board took the decision based on recommendations by a three-man disciplinary panel, IOC spokeswoman Giselle Davies said.

Thanou and fellow Greek sprinter Kostas Kenteris missed doping tests on the eve of the 2004 opening ceremony, claiming they were injured in a motorcycle accident. Both eventually pulled out of the games and were banned for two years by the IAAF, the world's governing body for athletics.

There are 13 gold medals at stake today.