American swimmers Aaron Peirsol and Natalie Coughlin have each set world records at the U.S. Olympic swimming trials in Omaha, Nebraska, while Michael Phelps claimed berths to the Beijing Games in two more events.

Peirsol topped a strong field in the 100-meter backstroke Tuesday with a record time of 52.89 seconds.  That broke the world mark he set at last year's World Championships in Australia by nine-100ths of a second.  Matt Grevers finished second to qualify for the Olympics in 53.19 seconds.
Meanwhile, Natalie Coughlin set her second world record in two days.  Coughlin clocked 58.97 seconds to become the first woman to break 59 seconds in the 100-meter backstroke.  On Monday, she set a world record of 59.03 seconds in a preliminary heat.

Michael Phelps continued his quest to equal or better countryman Mark Spitz's record of seven gold medals at one Olympics.  He won the 200-meter freestyle in one minute and 44.10 seconds to secure his berth in the individual event and the 4 x 200-meter freestyle relay.

Some information for this report was provided by AFP and AP.