After their brief embrace, Hansen swam off in one direction, Kosuke Kitajima the other.

Until the next time.

On a night when Roland Schoeman and Jessica Hardy set world records - one to be expected, the other a shock - Hansen regained the upper hand in one of swimming's fiercest rivalries.

Hansen holds world records in both the 100- and 200-meter breaststroke, but Kitajima beat him in those events at the Athens Olympics last summer.

Eager for redemption, Hansen jumped in the pool at the world swimming championships - with Kitajima in the very next lane for the 100m final.

``Not many people get a second chance,'' Hansen said, ``so I didn't want to screw it up twice.''

He did not, taking control in the first 50m and touched first in 59.37 seconds, just off the world mark of 59.30 he set at last year's US Olympic trials but a new meet record. Kitajima was second in 59.53.

When Hansen saw his name atop the scoreboard, the American star pounded the water in delight. France's Hugues Duboscq won bronze.

``Everyone keeps asking me, `What was that extra thing I had tonight?''' Hansen said. ``It was definitely emotion.''

Kitajima is not ready to concede. Not by a long shot.

``Hansen seems to be very confident and I assumed he would be very happy to avenge the Athens Olympics,'' the Japanese star said. ``This time I lost, but at the next world championships, I think I could beat him.''

Michael Phelps seemed to be back on form, posting the best time in the semifinals of the 200m freestyle.

But his first individual medal of the worlds will have to wait at least until he finally gets a much-anticipated race against Australia's Grant Hackett.

Schoeman captured the 50m butterfly and broke the world record he set just a day earlier in the semifinals. He held off American Ian Crocker in a furious dash from one end of the pool to the other, touching in 22.96 seconds.

Sergiy Breus of Ukraine took bronze in the non-Olympic event.

``Not bad for an African,'' said Schoeman, a three-time medalist in Athens whose one-day-old record was 23.01. ``I'd like to dominate the sprints in the future. I'll give it a shot.''

Hardy, an 18-year-old American swimming in her first international event, seems to have quite a future after her stunning performance in the semifinals of the 100 breaststroke.

The teenager from Long Beach, California, got off the block quicker than anyone and never faltered down the stretch, posting a time of one minute, 6.20 seconds.

That broke the record of 1:06.37 set two years ago by Australia's Leisel Jones at the Barcelona world championships.

``It's one of the great things about our team,'' said American captain Natalie Coughlin. ``We are so young, and we have swimmers like Jessica Hardy who can drop two seconds and seemingly come out of nowhere.''

Jones will get a chance to reclaim the record in the final. She was the second-fastest qualifier at 1:06.93.

``My goal was to make the finals,'' the Australian said.

The Australians went one-two in the women's 100m butterfly. Jess Schipper claimed gold with a meet record of 57.23, just 14-hundredths of a second ahead of countrywoman Libby Lenton. Poland's Otylia Jedrzejczak took the bronze.

``I can't believe it,'' Schipper said. ``Everything's turning really hard in my head.''

The US won its second gold of the day when 16-year-old Katie Hoff, who was overcome by nerves in her Olympic debut at Athens, won the 200m individual medley.

Phelps

put up the best time in the 200m semifinals, 1:46.33, while an energy-conserving Hackett settled comfortably in fourth.

Hackett, who has the 800m free preliminaries to come, did not want to burn himself out in the 200m. He was pleased with a time of 1:47.66.

``It was a really controlled swim,'' Hackett said.

``I wanted to do it with a minimal amount of energy.''