Olympics - Swimming: Michael Phelps underlined his determination to dominate the swimming with the destruction of the world record in the 400 metres Individual Medley as he picked up his first gold of the 2008 Beijing Games.
Phelps, who is looking to surpass Mark Spitz's long-standing record of seven golds at a single Olympics, was under world-record pace right from the start and eclipsed his own mark by an astonishing 1.41 seconds with a time of 4 minutes 3.84 seconds.
Hungarian Lazlo Cseh touched in second place in a European record time of 4:06.16, while Ryan Lochte took third, almost two seconds further adrift as Phelps decimated the field.
"I told Bob (Bowman, Phelps' coach) that this would be my last 400 IM, so I've got to go out there and get a good time," said Phelps. "And this was a good time."
Phelps' race was witnessed by United States president George W. Bush and his entourage, but the Baltimore native remained unfazed by the presence of so many dignitaries.
"Afterwards I looked up and saw President Bush giving me the thumbs up and holding up the American flag. That was pretty cool," he said.
"I was pretty emotional after that race. I was not that comfortable in the first 200m."
In the women's 400 metres Individual Medley Australian Stephanie Rice matched Phelps by destroying the world record in her event.
Rice and Zimbabwean swimmer Kirsty Coventry became the first women to go under 4:30 while Katie Hoff from the United States finished third, just outside the world record she set at the American trials.
Australian star Grant Hackett saw his hopes of a medal in the 400m freestyle dashed by South Korean Park Tae-hwan, who took gold in a time of 3:41.86 ahead of China's first medallist in the pool, Zhang Lin, and American Larsen Jensen.
Aisling Cooney, meanwhile, got her first taste of the Olympic experience in the women's 100 metres backstroke heats.
The Dublin teenager, seen as a prospect for the 2012 Games in London, was unable to better her own Irish record but a time of 1 minute, 2.5 seconds was an encouraging effort although not enough to reach the semi-finals.
The Olympic record was broken three times in the heats, Russian Anastasia Zueva first dipping under Natalie Coughlin's mark before Japanese swimmer Reiko Nakamura lowered the mark further in the next heat with a swim of 59.36 seconds.
But Zimbabwean Kirsty Coventry demolished that time - missing the world record by just 0.03 secs - with a swim of 59.00 secs to qualify fastest for the next round.