Cody Simpson caused a sensational upset on Day one (18 May) of the 2022 Australian Swimming Championships in Adelaide by beating Olympic gold medallist Kyle Chalmers.
The 25-year-old pop star, who returned to serious swimming training in 2019, won his men's 100m butterfly heat in a FINA World Championships qualifying time of 51.79.
Simpson will progress to the final later today as the second-fastest qualifier behind defending champion Matt Temple, who clocked a blisteringly quick 51.64.
Chalmers, who won 100 freestyle gold at Rio 2016 and silver at Tokyo 2020, was third quickest.
The top three in the final under the World Championships 'A' qualifying standard of 51.96 will also qualify for the 2022 Commonwealth Games in Birmingham (UK), beginning in July.
Elsewhere in the morning's prelims, Shayna Jack made a successful return from a two-year suspension with victory in her women's 100 free heat.
Her time of 53.27 was joint-second quickest with Meg Harris, behind Mollie O'Callaghan in 52.83.