South Africa's Tatjana Schoenmaker smashed another Olympic record on Wednesday when she won her heat in the 200m breaststroke in Tokyo.
Schoenmaker missed out on the world record by just 0.05 seconds, but her 2:19.16 obliterated the field as she qualified fastest for the semi-finals, which take place at 04:54 (SA time) on Thursday.
Schoenmaker is the overwhelming favourite to win the gold medal to add to the silver she won in the 100m breaststroke on Tuesday.
Kaylene Corbett, meanwhile, was the surprise package from a South African perspective as she swam beautifully to win her 200m breaststroke heat in 2:22.48.
She joined Schoenmaker in progressing to the semi-finals, having qualified 4th fastest after the heats.
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There was bad news for Erin Gallagher, who finished 2nd in her 100m freestyle heat in a time of 54.75 but could not qualify for the semi-finals.
Gallagher looked like she was on her way to win the heat for most of the race, but a late surge by Finland's Fanny Teijonsalo got the job done in 54.69.
SA's Martin Binedell, meanwhile, finished 2nd in his 200m backstroke heat in a time of 1:58.47 and that, too, was not quick enough to progress.