Johannesburg - Oscar Pistorius withdrew from the 400m race at the South African disabled championships in Durban on Wednesday, ending a tough meet for the double-amputee Olympic hopeful.
Agent Peet van Zyl said Pistorius was struggling with a blister on his leg which made it "very uncomfortable" to run, although the withdrawal was "more precaution than anything else."
Pistorius experienced a rare defeat in disabled competition in the 100m on Monday when he finished second to fellow South African Arnu Fourie. Pistorius hadn't run the 100m in nearly a year and Fourie is a single-amputee runner.
Pistorius then made a mistake during the final changeover in Tuesday's 4x100m that led to his team being disqualified.
Pistorius is expected to compete at South Africa's able-bodied nationals next month before travelling overseas. He needs one more Olympic-qualifying time in the 400m at an international event to be eligible for the London Games, according to criteria agreed on by national federations of Athletics South Africa and the South African Olympic committee.
He ran 45.20 this month to go inside the able-bodied qualifying time of 45.30 for the second time.
He needs to make that time once more overseas before the qualifying cut-off of June 30. Should he go to London, he'd make history as the first amputee track athlete to run at the Olympics.