Holland's Inge de Bruijn took the 50 metre butterfly world crown in Japan as team-mate Pieter van den Hoogenband laid down a challenge to Ian Thorpe.

While de Bruijn was utterly commanding, former great Michael Klim flopped, losing his 100m butterfly title to Lars Frolander.

And a new young talent was born in the 200m breaststroke as American Brendan Hansen came from nowhere to upset favourite Ed Moses.

Olympic champion Diana Mocanu of Romania won the women's 200m backstroke while Italian Massimiliano Rossolino added the 200m individual medley gold to his growing international medal tally.

Van den Hoogenband made it clear he is in no mood to relinquish 100m glory to Thorpe, his 200m conqueror.

The Dutch star set a new championship record with his 48.57 semi-final swim, breaking Alexander Popov's 1998 record.

Thorpe was on his shoulder to finish in 48.96 - a personal best time in a distance that isn't a favourite. The final is on Friday and the world record is 47.84, set by van den Hoogenband at the Olympics last year.

De Bruijn was also at her best, her sinewy frame skipping through the water to win in 25.90, outside her world record of 25.64 but the fifth fastest time ever.

Therese Alshammar and Anna-karin Kammerling took silver and bronze for Sweden.

While she continues to dominate, it appears Klim, four years younger, has seen better days. The Australian won seven medals, including four gold, at the last world championships in Perth and was the defending 100m butterfly champion, but could only manage seventh.

America's Ian Crocker took silver, Australia's Geoff Huegill the bronze.

"I'm a very happy man because I've now won the world championships, the European championships and the Olympics," said Frolander who set a new championship record of 52.10.