Sprinter Simon Magakwe rediscovered his gas pedal at the Golden Spike meet in Ostrava on Tuesday night, but Caster Semenya failed to escape the poor form that has hampered her season so far.
Magakwe finished fourth as he clocked the second-best time of his northern summer campaign. He ran 10.19sec in a race won by American Justin Gatlin in 9.86, the fastest time in the world this year.
Mike Rodgers, also of the US, was second in 10.08 and 38-year-old veteran Kim Collins of Saint Kitts and Nevis was third in 10.12.
Magakwe, who broke 10 seconds at the South African Championships in April though, should be pleased with his effort - though it was slower than the 10.13 he managed in Eugene, Oregon, last month.
Since then, he had run 10.20, 10.27 and 10.28.
Semenya finished last once again in the women's 800m, this time clocking 2min 3.91sec in a slow race won by Winnie Nanyondo of Uganda in 1:59.77.
The 2012 Olympic silver medallist was well positioned early on, sitting in the top three for much of the first lap, but at the bell she went backwards into obscurity, ending more than a second slower than she managed in Rome earlier this month.
Of the 14 runners who crossed the line, eight achieved personal bests, season's bests, or in the case of Nanyondo, a national record.
Semenya has resembled an ambling alp rather than the powerful finisher who broke two minutes every season since 2009 in Europe.
Her performances have kept her out of the Commonwealth Games in Glasgow from July 23 to August 3.
Wenda Nel, one of SA's medal hopefuls in Scotland, ended fourth in the women's 400m hurdles and tweeted later that she had made some technical errors.
Wouter le Roux was fifth in the men's 400m hurdles in 50.15.
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