Irvine - Kathleen Baker sliced more than half a second off her personal best to win the women's 100m backstroke at the US swimming championships in a world record of 58.00 on Saturday.
Baker had been gunning for the Kylie Masse's world record of 58.10 ever since she finished runner-up to the Canadian at the World Championships in Budapest last year.
That was another silver medal performance for Rio Olympics runner-up Baker, and just more motivation for a swimmer who now has her sights set on breaking 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," Baker said.
"I just broke that, so now I'm going to put 57.99 down."
Baker, who shared 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.
But it took her a moment to realise what she'd accomplished.
"I was looking to see if I won first, and then I realised I went 58.0 and I was shook," she said.
"I was like 'Oh my gosh I just broke a world record!'"
While there was no world record for Ledecky, her distance dominance was on full display as she shredded 400m field.
On pace to break her own world record of 3:56.46 through the first 250m, Ledecky professed herself satisfied with a time under four minutes, with expectations she'll 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 3.12 ahead of runner-up Leah Smith. Haley Anderson was third, 8.12 behind.
"I wanted to put myself through some pain tonight," said Ledecky, who added the 400m freestyle title to convincing victories in the 200m and 800m freestyles.
She was skipping the 1 500m freestyle on Sunday, opting instead to get back to training for a few more days before heading to Tokyo for her first major international meet since turning pro 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."
World record-holder Lilly King won the 100m breaststroke in 1:05.36, with Katie Meili finishing second in 1:06.19 and Micah Sumrall - the surprise 200m breaststroke winner - third in 1:06.34.
The men's 100m breaststroke went to Michael Andrew, the former age group sensation who says his first goal in the senior ranks is to dominate the sprint distances in all four strokes.
Andrew, 19, was fifth at the turn but powered home to win in 59.38.
"It's huge," said Andrew, whose victories in the 50m breaststroke and 50 butterfly hadn't secured his Pan Pacs berth.
In a duel of the past two Olympic champions, Ryan Murphy edged Matt Grevers in the 100m backstroke.
Murphy, double gold medalist in Rio in 2016, completed a sweep of the 50m, 200m and 100m backstroke in 52.51. Grevers, the 2012 100m backstroke gold medalist was second in 52.55.