BEIJING  - Japanese swimmer Kosuke Kitajima and Chinese gymnast Yang Wei led a golden day for Asia on Thursday that showcased the continent's growing sports power.

China's gymnast Yang Wei bites his gold medal after winning the men's individual all-around competition at the Beijing 2008 Olympics in Beijing, August 14, 2008.[Agencies]

As hosts China powered ahead in the medals table on the sixth day of the Games, three of the biggest names in Beijing, Roger Federer and sisters Venus and Serena Williams, crashed out of the tennis singles at the quarter-final stage.

Kosuke Kitajima of Japan celebrates with his gold medal for the men's 200 meters breaststroke swimming final at the National Aquatics Center during the Beijing 2008 Olympic Games August 14, 2008. [Agencies]

In the Water Cube, Asia's greatest swimmer Kitajima stole the spotlight from American Michael Phelps with an unprecedented "double-double" in the breaststroke, adding the 200 meters gold to the 100 title he won on Monday. He won both in Athens in 2004.

"I was not thinking about winning two gold medals at two consecutive Olympics," he said. "I was just focused on doing my best in Beijing."

There were sweet victories too for Chinese gymnast Yang Wei, who ended eight years of hurt in the men's individual all-round event, and for shooter Du Li, who had broken down in tears after failing to win the first gold of the Games on day one.

China even took an unexpected gold in women's archery thanks to Zhang Juan Juan. That ended South Korea's streak of winning every women's Olympic archery gold medal since 1984.

Asian nations have won nearly half of the golds so far.

Mongolia joined the party, taking the first gold medal in its history when Tuvshinbayar Naidan won the 100kg judo, rolling his opponent over three times in a show of brute force.

The Water Cube again saw plenty of excitement.

France's Alain Bernard won swimming's blue riband event, the men's 100 freestyle, by a whisker.

Stephanie Rice, the glamour girl of Australian swimming, took her third gold of the Games in the 4x200m freestyle relay.

Then hosts China scored a shock one-two in the pool.

Nineteen-year-old Liu Zige destroyed the world record in the women's 200 butterfly and compatriot Jiao Liuyang relegated Australian world champion Jessica Schipper to third.

"I just took it easy," winner Liu said of home pressure, maintaining calm. "I am always like this."

China have dominated gymnastic in these Games, and Yang, unbeaten on the international stage since 2006, followed team gold with another in the men's individual all-round event.

Thumping his chest and cupping his hands around his ears, he basked in the crowd's cheers even before the judges' final scores were announced. His joy was magnified by past disappointments -- taking silver in Sydney and missing out on a medal in Athens.

There was relief too for Chinese shooter Du, who steadied earlier nerves to win the women's 50m rifle three positions. Du said she had nearly quit the sport after failing to win a medal on Saturday, when national hopes had weighed heavily.

Rainstorms caused delays in tennis, softball, canoeing and rowing. Beach volleyball players struggled on though, squelching through the sand.

When the tennis resumed, the quarter-final shocks occurred.

Top men's seed Roger Federer lost 6-4 7-6 to American James Blake after an error-strewn performance from the Swiss.

"I'd lost to him eight, nine, 10, 50 times, I don't know how many, but I had the feeling it could be my day," said Blake.

Then Serena Williams was surprisingly beaten 3-6 6-4 6-3 by Russian Elena Dementieva, followed by sister and double Olympic champion Venus who lost 7-5 7-5 to China's Li Na.

China leads the overall medals table with 22 golds.

America are second with 10 golds -- five of those thanks to swimmer Phelps and relay team mates -- but will expect to come back strongly when track-and-field events start on Friday.

Germany are third with seven golds, followed by South Korea and Italy on six.

Replacing Russia as America's main challenger at the Olympics, China came second in Athens and are mounting a formidable challenge to go one better at home.

The world's most populous nation has shown its new wealth, confidence and technological ability with a dazzling opening ceremony and architecturally eye-catching venues.