The United States won two of the four swimming gold medals on offer on Monday night at the 12th FINA World Championships at Melbourne's Rod Laver Arena.

American Brendan Hansen held off reigning Olympic and world champion Kosuke Kitajima in the men's 100m breaststroke. Hansen raced to an early lead and was fractionally ahead of world-record pace at the turn. It was a pace that the American could not keep up as the Japanese began to make his move setting up a thrilling finish, Hansen digging deep in the final strokes to win in 59.80 seconds. Kitajimi finished 0.16 seconds behind, with Australian Brenton Rickard finishing third -- remarkably the first time an Australian has medalled at this event.

Libby Lenton won her second gold of the meet in a stunning finish to the woman's 100m butterfly, achieving a new championship record of 57.15. The event was expected to be a two-horse race between Lenton and fellow Australian Jessicah Schipper, but American Natalie Coughlin was intent on crashing the party.

She came out strongly, hitting the wall at the halfway mark with a handy lead, and continued to look strong until about the midway part of the second lap when the American started to tire, opening the door for the two Australians. Lenton, with a narrow lead in the final metres, timed her dive at the wall perfectly, her smoother approach at the finish giving her the edge in one of the most exciting finals of the championship to date.

American 'teenager Katie Hoff successfully defended her 200m individual medley crown, edging out veteran Zimbabwean Kirsty Coventry for the gold, as she had done in 2005. After a tight tussle with Coventry in the first two legs, Hoff made her decisive move in the breaststroke leg, breaking away from the pack to take an unassailable lead by the turn. Coventry's stronger freestyle made little difference in the end with Hoff winning by half a body-length. Australian Stephanie Rice finished third.

In the last of the night's finals, Roland Schoeman was never troubled in the 50m butterfly. The South African has dominated the non-Olympic event in recent years and made no mistake in Melbourne, emerging half a body-length ahead of his rivals at the start and from there it was clear sailing for the world record holder. Ian Crocker of the United States finished second, while Denmark's Jakob Ankjaer just nudged out Venezuelan Albert Subirats Altes for bronze.