The 24-year-old flew through his 50 metre freestyle heat in 23.06 seconds, less than a second slower than the qualifying A-time for the Olympic Games in London later this year.

However, the time was academic for the American-based Louw, who has already met the first part of a SA Sports Confederation and Olympic Committee (Sascoc) policy that requires its swimmers to record an Olympic A-standard time twice during a 10-month period, including once at the national trials in April.

Hungarian Krisztian Takacs was second quickest in 23.37, while there were also impressive showings from Pretoria-based Werner Bosman (23.70) and Bloemfontein swimmer Reynard Wessels (23.76), who will all take part in the final on Sunday evening.

Elsewhere, Olympic hopeful Karin Prinsloo impressed in the 100m freestyle and 100m backstroke events with the quickest qualifying times.

The Tuks Swimming Club member recorded 56.14 in the freestyle, 1.57 seconds slower than the mark for London and was 2.61 seconds off in the 100m backstroke, although she managed to finish ahead of Zimbabwe's double-Olympic gold medallist in both.

Other Olympic hopefuls Vanessa Mohr (58.77) and Trudi Maree (57.95) will also take part in the 100m freestyle evening final.

Chad le Clos won all three heats he took part in, the 100m butterfly, 200m freestyle and 200m Individual Medley (IM), to seal a place in the finals.

He had the third, second and eighth fastest times, although two of the races were not his regular ones.

The 200m IM is the only one of his possible Olympic events and he still needs a time in, which is a possibility in the later final.

In the 100m butterfly, Dylan Bosch did impress with his time of 54.74, just short of the 52.36 Olympic qualifying time.

Finally, in the 100m breaststroke, Cameron van der Burgh came second in his heat with a time of 1:05.56 to Chad McKenzie (1:04.90) to qualify for the final.

Another London hopeful, Neil Versfeld, was the quickest qualifier over the distance with a time of 1:04.49.