Olympic hopefuls Caster Semenya and Oscar Pistorius are scheduled to compete at this week's South African championships.
Semenya will run in the 800 meters, while double-amputee Pistorius will run in the 400.
Semenya, a silver medalist at last year's world championships, needs to run 1 minute, 59.90 seconds or better to qualify for her first Olympics. The former world champion ran a sluggish 2:03.60 in her season debut last month — her first two-lap race under new coach and Olympic great Maria Mutola.
Pistorius needs one more qualifying time of 45.30 seconds in an international event to make history as the first amputee runner to compete at the Olympics. He ran 45.20 at a meet in Pretoria on March 17, the second time he's gone inside the able-bodied qualifying time for London.
Athletics South Africa has said athletes hoping to go to the Olympics must compete at the two-day nationals that start Friday in the south coast city of Port Elizabeth.
Pistorius will likely compete at one more meet in South Africa in early May, his agent Peet van Zyl said, before kicking off his international season at the BT Paralympic Cup in Manchester, England, at the end of next month.
Pistorius also hopes to run at IAAF events in Ostrava and Hengelo, and Diamond League meetings in Eugene, Ore., and New York as he chases a place in the South African team and a shot at Olympic history.