The 22-year-old from KZN led from start to finish, touching the wall first in a time of 3:47.96 – well inside the international Qualification Time Standards (QTS) of 3:50.87 for the Fina World Long Course Championships in Kazan later this year.
Calvyn Justus (3:55.39) was second fastest and Jarryd Baxter (3:55.62) third, but both will have to better their times in the final if they want to secure their tickets to Russia in the same event.
The April 13-19 meet doubles up as the trials for the July and August World Championships in Kazan, with participants needing to meet the QTS in order to have a chance of making the team.
In other races from the opening session of the competition, four-time Olympian Roland Schoeman was the quickest in the 50m butterfly with a time of 24.16, while reigning Olympic 100m breaststroke champion Cameron van der Burgh was the top finisher in the same event thanks to a time of 1:01.66.
Amongthe women, Vanessa Mohr (1:00.58) from Northern Tigers was the fastest through the 100m butterfly heats as she booked her place in the evening semifinals ahead of Marne Erasmus (1:01.10) and Erin Gallagher (1:02.97).
Another Tigers swimmer Marlies Ross topped the 200m individual medley heats in a time of 2:17.70, ahead of Rene Warnes (2:19.51) and Kirsty McLauchlan (2:20.66).
Western Province’s Jessica Ashley-Cooper edged the 50m freestyle heats from Trudi Maree (26.48) in 26.17 seconds.
Finally, the quickest in the 400m freestyle heats was the country’s top female swimmer, Karin Prinsloo, who clocked 4:18.99. Kate Beavon (4:20.86) came in second, followed by Caitlan Kat (4:21.05).