MANCHESTER, England, May 14 — As Oscar Pistorius of South Africa crouched in the starting blocks for the 200 meters on Sunday, the small crowd turned its attention to the sprinter who calls himself the fastest man on no legs.

Pistorius wants to be the first amputee runner to compete in the Olympics. But despite his ascendance, he is facing resistance from track and field’s world governing body, which is seeking to bar him on the grounds that the technology of his prosthetics may give him an unfair advantage over sprinters using their natural legs.

His first strides were choppy Sunday, a necessary accommodation to sprinting on a pair of j-shaped blades made of carbon fiber and known as Cheetahs. Pistorius was born without the fibula in his lower legs and with other defects in his feet. He had both legs amputated below the knee when he was 11 months old. At 20, his coach says, he is like a five-speed engine with no second gear.

Yet Pistorius is also a searing talent who has begun erasing the lines between abled and disabled, raising philosophical questions: What should an athlete look like? Where should limits be placed on technology to balance fair play with the right to compete? Would the nature of sport be altered if athletes using artificial limbs could run faster or jump higher than the best athletes using their natural limbs?