U.S. swimmers slay records in Durban

DURBAN, South Africa (Reuters) -- American Jessica Hardy bettered her own 50m breaststroke short course world record at the World Cup on Saturday.

Hardy swept home in 29.45 seconds to beat her previous mark of 29.58 set in Manchester, England in April 2008.

"I haven't been swimming as well as I would have liked so to have started so well in the World Cup series is great," Hardy told reporters.

"It was an easy swim and I would have been happy with just a good time," she added.

The 22-year-old was in control of the race from the start as she held off the German pair of Kerstin Vogel, who finished second in 30.57, and Caroline Ruhnau who came third in 31.01.

Fellow American Peter Marshall broke the men's 50m backstroke world record after stopping the clock in 22.75 seconds. His time eclipsed the previous mark of 22.87 set by compatriot Randall Ball in Berlin last November.

"I thought I had a good chance of breaking the record," the 27-year-old told reporters. "I felt pretty good swimming the 100 [on Friday] and my sprinting is pretty good at the moment.

"As the [World Cup] series goes on my endurance will improve which will improve my 100 metres times."

Marshall was rarely tested in the 50, comfortably holding off second-placed Stanislav Donets of Russia (23.63). Ashley Delaney of Australia was third in 23.74.

Sweden's Therese Alshammar began -- and ended -- her day with world records. She set the women's 100m IM mark in the morning qualifying session, touching the wall in 58.51 to beat the previous standard of 58.84. Hours later in the final event of the meet -- the 50m butterfly -- she set a new low with a time of 24.75 to beat Marieke Guehrer's mark of 24.99 set last November.

"I am usually a sprint butterflier -- I haven't swum the 100 IM in a very long time," Alshammar said after her first record on Saturday. "I went into the race just to see where I was at and if it was an event I might consider doing in the future."

The Swede, who won silver medals in the 50m and 100m freestyle at the Sydney Olympics in 2000, said her training regime and a growing maturity helped her set records.

"I had a great year in the pool last year and then I trained for six months in Sydney. It was a great experience and I learnt not to expect too much too soon and when things happen for you it makes it all the more special," she said.

"I hope for more world records otherwise I wouldn't be standing here."