IRVINE (California) • Kathleen Baker sliced more than half a second off her personal best to win the 100m backstroke at the United States swimming championships in a world record of 58.00sec on Saturday.
She had been gunning for Kylie Masse's world record of 58.10 ever since she finished second to the Canadian at the World Championships in Budapest last year.
That, coupled with her silver medal at the Rio Olympics, gave Baker more motivation and she is aiming to break through the 58-second barrier.
"I put a goal on my phone so it reminds me every day and right now it's a 58.10," said the 21-year-old. "I just broke that, so now I'm going to put 57.99 down."
Baker, who shared the 200m backstroke gold with 16-year-old Regan Smith this week, led a podium that featured three women under 59 seconds, with 50m back winner Olivia Smoliga second in 58.75 and Smith third in 58.83.
Hers was the first world record of the five-day championships, which serve as a qualifier for both the Pan Pacific Championships next month in Tokyo and the World Championships in South Korea next year.
Baker said she fed off the energy of Katie Ledecky - who stirred up the crowd as she briefly pushed world-record pace on the way to a 400m freestyle victory in 3:59.09.
While there was no world record for Ledecky, her distance dominance was on full display as she shredded the 400m field.
On pace to break her own world mark of 3:56.46 through the first 250m, Ledecky professed herself satisfied with a time under four minutes, with expectations she will improve at the Pan Pacs coming up in less than two weeks.
"It's always good to go under four (minutes)," said Ledecky, who touched 3.12sec ahead of runner-up Leah Smith.
"I wanted to put myself through some pain tonight."
She added the 400m free title to convincing victories in the 200m and 800m freestyles and will skip the 1,500m free to get back to training for a few more days, before heading to Tokyo for her first major international meet since turning professional in March.
"I haven't really had an off swim," Ledecky said of her season so far. "I feel like I'm in a good spot."
Haley Anderson was third, 8.12sec behind.