Jenny Thompson rode a "calm, peaceful feeling" to break Mary T. Meagher's 18-year-old 100-meter butterfly mark during a record rush at the Pan Pacific swimming championships today.

Thompson, 26, was visibly shaken after eclipsing the second-oldest record in swimming, set by Meagher on Aug. 16, 1981. But before the race, Thompson said she underwent a transformation which helped her.

"I couldn't even believe it," Thompson said. "I didn't feel that great yesterday, this morning or even in the warmup tonight. Then, when I was coming out for the race, I felt that calm, peaceful feeling and I knew things were going to be okay."

Australia's Ian Thorpe broke his second world record of the meet, in the 200 freestyle, while South Africa's Penny Heyns got her fifth world record in five races in the 100 breaststroke.

Thompson, a five-time Olympic gold medalist, had a time of 57.88 seconds to lower the mark of 57.93 set by Meagher and break the fourth world record in two days at the championships.

"The record used to seem like a long shot," Thompson said. "My time's been dropping little by little and it's seemed more like a reality each time. Tonight I didn't know where I was in the race but I just kept going and hoped it was there."

Thompson was followed by Australia's Susie O'Neill, who will attack swimming's oldest record--Meagher's 200 fly mark set three days before the 100 record.

"It was awesome, I feel so good for Jenny," O'Neill said. "She's done it, now I want to do it."

Thompson has never won an individual gold at an Olympics but is favored to take the event in the same pool at the 2000 Summer Games.

The 16-year-old Thorpe added the 200 record to the 400 he set on Sunday. His time of 1 minute 46.34 seconds came in a semifinal heat that included previous record holder Grant Hackett, who went 1:46.67 earlier this year.

Heyns broke her fifth record in five races, as her time of 1:06.52 broke her own record of 1:06.95 set at the Janet Evans Invitational in Los Angeles on July 19.

At that meet the Olympic champion broke the 100 and 200 records twice each.

"If you know me you'll know that I quite often run hot in the morning, so it wasn't a big surprise," Heyns said. "I never really go for a world record, I just go out for a personal best."