The Western Province swimmer flew through to win her race in a time of 25.60 seconds, marginally outside the A-standard mark of 25.27.
She was almost half-a-second clear of Karin Prinsloo (26.03), while Lehesta Kemp was third fastest in 26.34.
No female swimmer had a previous Olympic time in the event prior to the meet, though, there is every chance that if one is produced in the final later in the day, they could make the team for the 2012 London Games.
Elsewhere, Suzaan van Biljon, who guaranteed her selection for the Games in the 200m breaststroke earlier in the week, was the fastest in both the heats and semi-finals of the 50m race as she swam 33.14 and 32.93, respectively.
Her semis time was marginally faster than Taryn Mackenzie (33.10), with Tara Nicholas (33.48).
In the men's 50m breaststroke, Warren Karsten reigned supreme in a time of 28.95, with Jared Pike second best at 29.27.
Backstroke specialist Charl Crous, who also booked his place in Team South Africa this week, topped the 50m distance on his way to the final with a 26.37, ahead of Darren Murray (26.43).
In the women's race, Australian Sophie Edington was quickest with a 29.89 time, finishing in front of Jessica Ashley-Cooper (30.22).
Vanessa Mohr (27.00) topped the 50m butterfly semifinalists, while Brett Walsh (24.74) was quickest on the men's front.