Phelps, Thorpe star on opening night

Michael Phelps made the perfect start to his bid to win a record eight gold medals at the Athens Olympics when he broke his own world record to win the 400 metres individual medley yesterday.

Australia's Ian Thorpe, the swimming star of the Sydney Olympics, also got off to a flying start in Athens when he successfully defended his 400 freestyle title after a titanic struggle with Grant Hackett.

Australia won a second gold medal on the opening night of the swimming with a world record in the women's 4x100 freestyle relay, while Ukraine's Yana Kochklova confirmed her position as the world's best all-round female swimmer when she retained her individual medley title.

American Phelps lived up to all the hype that has surrounded him since he announced he would try and better Mark Spitz's seven gold medals from the Munich Games.

The 19-year-old pulled away from his rivals to win the gold in four minutes 08.26 seconds and shave 0.15 seconds off the previous mark of 4:08.41 which he set in California last month.

Erik Vendt finished second in 4:11.81 to complete a US one-two while Hungary's Laszlo Cseh took the bronze in 4:12.15 but neither was able to mount a serious challenge to Phelps.

"I've got one event down and six to go so I'm a little less nervous. I've got one off my shoulders," said Phelps, whose swimming is better than his maths.

Thorpe won the 400 freestyle in 3:43.10 in a close finish from Hackett (3:43.36) and American Klete Keller (3:44.11) to join fellow Australian Murray Rose (1956 and 1960) as the only men to win back-to-back 400 freestyle Olympic golds.

Thorpe, who won three gold medals in Sydney, has not lost a 400 freestyle race in seven years but was disqualified for a false start at the Australian trials and only defended his title after Craig Stevens stepped down.

"There was a lot that went on before this race and I'm more excited with the fact that it's over now," Thorpe said.

Klochkova became the first woman to win back-to-back Olympic 400 individual medley gold medals but was pushed all the way by American Kaitlin Sandeno, who was in front turning for home.

The Ukrainian reeled her in over the final few metres to win gold in 4:34.83, just 0.12 ahead of Sandeno. Georgina Bardach of Argentina got the bronze.

Australia won the women's 4x100 freestyle relay for the first time since 1956 after a brilliant last leg from Jodie Henry.

Australia were in front after Alice Mills and individual world record holder Libby Lenton swam the first two legs but slipped behind after Petria Thomas' third leg.

American Jenny Thompson dived in first on the anchor leg but Henry flashed home to finish with a world record of 3:35.94.