LONDON — Oscar Pistorius bounced on his carbon-fiber blades in the sun at the start-finish line Thursday, waiting for his turn to run in the 4x400-meter relay. But the handoff never came.


Pistorius and his South African teammates did not get to finish their semifinal heat Thursday morning after their team’s second runner, Ofentse Mogawane, collided with Vincent Mumo Kiilu of Kenya on the final turn and tumbled to the track.


Seemingly eliminated by being in the wrong place at the wrong time, the South African team was instead reinstated on appeal about an hour after the race when track officials ruled that the Kenyan runner had obstructed his South African rival.


The incident came late in the second of the race’s four legs, as Kiilu led Mogawane at the back of the pack on the final turn. Kiilu moved off the rail just before the collision — to pass a slower runner — but that action put him right in the path of Mogawane, who clipped his heel, sending both runners down on the track.


Kiilu contended that Mogawane had spiked him, and he held up his shoe for reporters to show that it had a small cut in the heel. “I was spiked,” Kiilu said. “I was in the front, so somebody behind me spiked me.”


Mogawane, who dislocated his shoulder in the fall and was helped off the track by meet officials, called the incident an accident and seemed resigned to his team’s elimination.


But the race’s referee instead disqualified the Kenyan team, ruling Kiilu had caused the fall by cutting in front of Mogawane. Kenyan track officials watched video of the incident and agreed that Kiilu was at fault, according to a statement from Olympic officials.


But the referee cannot advance a team that did not finish a race, so South Africa appealed to a jury of appeal. Pistorius and his teammates were advanced to the final even though they had not finished the race, “considering that their chances had been severely damaged in the incident with Kenya,” the jury said in a statement.


South Africa will run as a ninth team in Friday night’s final, which is normally limited to eight, but the team is not expected to pose a challenge to the most serious medal contenders: the Bahamas, the United States, Trinidad and Tobago and Britain. They all qualified easily, and without incident.


Mogawane’s injury will cause him to miss the race, but Pistorius will get one last chance to run here.


The incident had appeared to end the Olympics for Pistorius, who runs on carbon fiber blades after having his lower legs amputated before his first birthday.


He learned to walk, and then to run, on prosthetic legs, and in recent years he waged a long campaign to compete in international competition against able-bodied runners. He worked through track’s governing body, arbitration and the courts to gain that right, appearing in major European meets and last year’s world championships in South Korea. But it was not until this year that he ran the qualifying time he needed to compete in London.


He made his debut in the 400 meters, advancing to the semifinals, and was also included in the relay. He was to run the third leg, and was lined up with runners from the other teams waiting for his chance, but Mogawane never rounded the final corner.


“I took my eyes off the screen and kept them on the straight, and obviously just as I took them off it must have happened because I looked down the straight and I was waiting for him,” Pistorius said. “He’s not the biggest of guys — I thought he was maybe pushed in behind someone — and then I just carried on looking, carried on looking and obviously he didn’t come out.”


The 4x400 is a more contentious relay than the flashier 4x100 sprint relay, in which each team must run in its assigned lane the entire race. In the 4x400, when only the first leg takes place in separate lanes, runners routinely jockey for position both during the race and in the exchange zone where handoffs take place. On Thursday, one runner had to hurdle another who fell after surrendering the baton.


“The second leg can get rough,” said Joshua Mance, who ran it for the United States in Thursday’s second heat.


That was one reason track officials decreed that Pistorius run the opening leg — in his own lane — at last year’s world championships. On Thursday he was to run third, but he never got the chance.


Before the appeal was announced, Pistorius had lamented the sudden, stunning end of his first Olympics.


“It’s been absolutely phenomenal,” he said of the experience. “Just stepping out today on a track in front of a crowd like this has been awesome. It would have been nice to have another run.”


Now he will.