Regan Smith set a new world record of 57.13 seconds in the 100m backstroke at the US Olympic trials in Indianapolis on Tuesday, issuing a strong challenge to Australia's Kaylee McKeown just six weeks before the Paris Games.

Smith broke the previous world record of 57.33 seconds set by McKeown in Budapest in October 2023. "It was part of the plan," Smith said, referring to reclaiming the record she initially held in 2019.

Having already lowered her American record to 57.47 seconds in the semi-finals, Smith delivered an impressive final push, with Katharine Berkoff hot on her heels, to slice two-tenths of a second off McKeown's record.

"I'm so proud of myself," Smith said, reflecting on her journey since earning 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 with a time of 57.91 seconds, ensuring a formidable US presence in the event for Paris, where McKeown remains a strong contender, having posted a 57.41-second time at the Australian trials last week.

In the men's events, Tokyo star Caeleb Dressel advanced to the 100m freestyle final with the third-fastest time in the semi-finals. Dressel, who won five gold medals in Tokyo, has been a subject of intrigue since stepping away from the sport during the 2022 world championships and subsequently missing the 2023 worlds after a nine-month hiatus.

Chris Guiliano led the semi-finals with a time of 47.25 seconds, while 21-year-old Jack Alexy won the second semi-final in 47.33 seconds, narrowly beating Dressel's 47.53 seconds. This marked Dressel's fastest time in two years, and he showed his satisfaction by beaming as he checked the scoreboard and shook hands with Alexy.