Versatile swimmer Chad le Clos provided South Africa's only shining light on the third day of the London Olympic Games on Monday.
Le Clos finished second behind Takeshi Matsuda of Japan in the faster of two semifinals in the men's 200 metres butterfly, clocking a national record of one minute, 54.34 seconds (1:54.34).
The 20-year-old South African, who was fifth in the men's 400m individual medley final on Saturday, qualified second fastest for Tuesday night's final.
American Michael Phelps won the other semifinal in 1:54.53.
"I'm obviously happy with the time. It is fantastic," Le Clos said.
"I was so relaxed going into this race. I don't know why, but I was actually nervous that I was too relaxed.
"I guess it worked out for me, and I just hope tomorrow night I can repeat tonight's performance."
Earlier, in the morning session, there were disappointing performances in the pool with Karin Prinsloo crashing out in her heat of the women's 200m freestyle.
Prinsloo finished seventh in 1:59.24 in her Olympic debut, but she will have another chance to make a splash in the 200m backstroke event.
Meanwhile, Kathryn Meaklim's Olympic campaign came to an end as she failed to progress beyond the heats of the women's 200m individual medley. She finished seventh in her heat in 2:15.25.
Elsewhere, a clinical hat-trick by Australian midfielder Jamie Dwyer helped his side to a 6-0 victory over the SA men's hockey team in their Pool A opener.
The South Africans conceded two penalty strokes and too many set-pieces as world No 1 Australia stamped their authority and set the benchmark for the rest of the tournament.
The SA women's rowing pair of Lee-Anne Persse and Naydene Smith missed out on qualifying for the A final, and a chance for a medal, after finishing fifth in the repechage in 7:18.96.
Persse and Smith will compete in the B final on Wednesday.
The country's only entrant in archery, Karen Hultzer, was eliminated in the first round of the women's individual event.
Hultzer, who was 46th of 64 competitors in last week's ranking round, won the third set against former European Championships bronze medallist Pia Lionetti, but the South African lost the match 6-2.
In beach volleyball, the men's team of Freedom Chiya and Grant Goldschmidt went down in straight sets, in their second successive group game, to the Latvian pairing of Aleksandrs Samoilovs and Ruslans Sorokins.
Judoka Gideon van Zyl was eliminated in the last 32 stage of the men's 73kg discipline by Rustam Orujov of Azerbaijan in four minutes and 34 seconds, bringing an end to his Olympic campaign.
The badminton team of Michelle Edwards and Annari Viljoen were eliminated from the women's doubles competition after going down to Greysia Polii and Meiliana Jauhari of Indonesia – their third successive defeat in the group stages.
And equestrian Alex Peternell was lying 56th of 59 remaining competitors after two events – dressage and cross country – in individual eventing.
Peternell, who won a case at the Court of Arbitration for Sport to be included as the only horse rider in the SA team, will compete in the final eventing discipline (jumping) on Tuesday.