Johannesburg - South African athletes were in poor form, with world 800m champions Mbulaeni Mulaudzi and Caster Semenya, and one-lap hurdler Cornel Fredericks all falling well short of their best at the Diamond League meeting in Lausanne, Switzerland, on Thursday night.
Fredericks went out hard in the men's 400m hurdles, leading through halfway, but faded to seventh place in a slow 51.12 seconds - almost three seconds off the personal best he set in Durban in April.
David Greene of Great Britain won the race in 48.41.
Mulaudzi was never in contention in his specialist event, trailing home in eighth position in 1:48.44, also falling nearly three seconds off the season's best set in Rome in May.
World record holder David Rudisha hit the front with 300m to go and broke clear to win comfortably in 1:44.15. Semenya struggled after stepping up in distance to the 1 500m discipline.
The 20-year-old, who hopes to compete over 800m and 1 500m at next year's London Olympics, fell off the pace after two laps and eventually finished 13th, and last, in 4:16.36.
Semenya was more than eight seconds off the career best she set to win the African junior title in August 2009.
Morgan Uceny of the United States won the race in 4:05.52. - Sapa