McKeown powered to the wall in a championship record 57.16s, with Smith having to once more settle for second, just 0.19s behind.

Katharine Berkoff, also of the US, took bronze.

McKeown’s victory underlines her status as the undisputed force in women’s backstroke.

“It’s always very nerve-wracking, especially off the back of the Olympics,” said the 24-year-old, who won the 100-200m backstroke double at the Tokyo and Paris Olympics.

“I was probably a bit more nervous than I would like to have been tonight.”

This was another chapter in the storied rivalry between arch-rivals Smith and McKeown.

The 23-year-old American Smith set a world record of 57.13s at the 2024 US Olympic trials, snatching McKeown’s world record.

However, McKeown got the better of the American to win gold at the Paris Olympics, relegating Smith into silver in both the 100m and 200m backstroke.

Ahead of Singapore, McKeown and Smith shared the 20 fastest times in history.