Gideon Louw was the best of the South Africans on the third last day of competition, qualifying for Saturday's 50m freestyle final.
Louw was sixth fastest in the semi-finals, clocking 22.02 seconds.
Triple Olympic medallist Roland Schoeman crashed out, however, finishing last of the semi-finalists in 22.42.
Chad le Clos, who was fifth in the men's 200m butterfly final on Wednesday, failed in his attempt to reach the 100m final.
Le Clos was 13th in the two-lap semi-finals in 52.44.
Teenager Vanessa Mohr, 16, placed 15th in the women's 50m butterfly semi-finals in 26.74.
South Africa, after securing two bronzes earlier in the week, dropped one place to 22nd on the medals table -- tied with Mexico -- with two days of competition remaining.