(Reuters)
Updated: 2007-08-01 11:31

CHICAGO - World record holders Brendan Hansen and Kate Ziegler opened the U.S. Swimming Nationals with solid wins on Tuesday while Michael Phelps began his busy week by failing to qualify for the final in the 200 metres breaststroke.

Swimmer Michael Phelps swims in the preliminaries of the 200-meter breaststroke at the US Swimming Nationals in Indianapolis, Tuesday, July 31, 2007. Phelps finished with a time of 2 minutes, 15.81 seconds, failing to qualify for the final. [AP]

Phelps, however, is almost certain to add to his 32 national titles as the 22-year-old swimmer gave himself a small taste of the enormous challenge ahead by competing in 10 events in Indianapolis.

The world's most versatile swimmer, Phelps will dive into the Indiana University Natatorium pool a potential 17 times in five days competing in the 200 and 400 free, 100 and 200 backstroke, 200 breaststroke, 100 butterfly and 200 medley and three relays.

Heavy workloads are not unfamiliar for Phelps, who returned home from the 2004 Athens Olympics with eight medals and secured seven golds from the world championships earlier this year in Melbourne.

Phelps, who rarely competes in the 200 breast, posted a personal best time of 2 minutes, 15.81 seconds, in the morning heats, but finished 11th and missed a spot in the A final by half a second.

In Phelps' absence, Hansen, who holds the world mark in both the 100 and 200 breaststroke, seized the spotlight powering to a comfortable victory in the 200 in 2:09.91, well shy of his record of 2:08.50.

Ziegler, who shattered swimming's oldest world record when she erased Janet Evans' 1,500m freestyle mark in June, touched first in the 800m freestyle in 8:22.33 but the world champion was chased to the wall by 400 individual medley world record holder Katie Hoff.

"After I broke the world record in 1,500 metres I think a lot of people expect me to do it every time I swim," Ziegler told poolside reporters. "But I just try to do my best."

Other winners on day one, included 17-year-old Kathleen Hersey, who followed up her four gold medals at the Panamerican Games, with a national title in the 200 butterfly, touching first in 2:017.19.

Rebecca Soni was an easy winner in the women's 200 breaststroke coming home in 2:23.62, over two seconds clear of Panamerican gold medallist Caitlin Leverenz.

Davis Tarwater took top spot on the podium in the 200 butterfly in 1:56.03 while two-time Olympian and double silver medallist Erik Vendt eased to victory in the 1,500 in 14:57.01.