Two Australians and one Japanese swimmer set world records Monday at the World Championships.
Matthew Welsh established a world record in winning the 50m butterfly gold, Leisel Jones established a new mark in the women's 100m breaststroke semifinals, and Kosuke Kitajima set a new standard in winning the men's 100m breaststroke gold medal.
In Monday's other medal events, American veteran Jenny Thompson won gold in the 100m butterfly and Yana Klochkova of the Ukraine won gold in the 200m individual medley.
Welsh covered his single swim down the pool in 23.43 seconds, beating the old record of 23.44 set by fellow Australian Geoff Huegill at the last worlds in Fukuoka, Japan. Afterward, Welsh looked over at Huegill, who finished fourth a few lanes down, with his arms wide apart in apparent disbelief.
"I had no pressure in that race being a backstroker," Welsh said. "I was really happy with my start and the kick felt fantastic all the way through."
Ian Crocker of the US won silver in 23.62, with bronze for Russian Evgeni Korotychkine in 23.73.
Barely 10 minutes after Welsh set his mark, Jones clocked 1:06.37 in the second semifinal heat of the 100 breaststroke, beating the old record of 1:06.52 set in 1999 by Penelope Heyns of South Africa.
"I think it was seeing Matt set a world record that inspired me," Jones said of her fellow Australian.
Kitajima's time of 59.78 in the men's 100m breaststroke came as three world marks fell in about 50 minutes in Palau Sant Jordi.
The Japanese eclipsed the old record of 59.94 set by Roman Sloudnov of Russia in Fukuoka in 2001. Brendan Hansen of the US took silver in 1:00.21, with bronze for James Gibson of Britain in 1:00.37.
Monday was the second of eight days of pool action and the three world records were the first of the championships.
Thompson, an eight-time Olympic champion, captured her first major individual gold since 1998. All eight of her Olympic titles have come in relays.
Thompson's time of 57.96 seconds beat silver medalist Otylia Jedrzejczak of Poland (58.22) and bronze medalist Martina Moravcova of Slovakia (58.24).
"It's great to come back after a year-and-a-half off and have this kind of success, so I'm really happy," said Thompson, who recently completed her second year of medical school and is planning to break from her studies to compete in next year's Athens Olympics.
"It was very close and I put my head down for the last four strokes, which may not have been smart," she added. "I had a pretty long finish and luckily I was the first to touch the wall."
Klochkova won the women's 200 individual medley in 2:10.75, the third fastest time ever. Alice Mills of Australia claimed silver in 2:12.75 and Zhou Yafei of China took the bronze in 2:12.92.
Thompson's teammate Natalie Coughlin finished eighth out of eight swimmers in the 100 butterfly final.
Earlier, Coughlin failed to qualify for the 100 backstroke semifinals, citing illness as the reason.
The American swam 1:03.18 in the backstroke, more than three seconds off her world record-time of 59.58 seconds set last year.
Coughlin, who said she has been ill since Saturday, apparently was weakened by her strong performance in the opening leg of the Americans' gold-medal effort in the 400 freestyle relay on Sunday night.
The 20-year-old California native has entered seven events -- the 100m and 200m backstroke, 100 free and 100m fly, plus three relays. She has been called the best American female swimmer in a generation and was billed to lead a strong US team with 18-year-old star Michael Phelps.