Regan Smith clocks 100m backstroke world record of 57.13 in US trials win
Smith eclipsed the world record of 57.33 set in Budapest in October 2023 by McKeown, who had swum the second-fastest time ever, 57.41, at the Australian trials last week.
"It was part of the plan," Smith said of regaining the record she held back in 2019.
She'd signalled her intentions by lowering her American record to 57.47 in the semi-finals and with Katharine Berkoff pushing her all the way at Lucas Oil Stadium she came up with a late push to slice two-tenths of a second off McKeown's mark.
"I'm so proud of myself," said Smith, who earned two silvers and a bronze at the Tokyo Olympics. "Backstroke is hard for me sometimes, but to fight back like this and get that back means a lot."
Berkoff finished second in 57.91 to set up a powerful US one-two punch in the event in Paris.