The man known as "Blade Runner" because of his carbon-fiber prosthetics will get a chance to run for an Olympic medal after officials accepted South Africa's protest over a collision and awarded an extra spot in Friday's final. Pistorius already is the first amputee to compete on a Summer Games track.
In the opening round Thursday, a Kenyan runner knocked into South Africa's Ofentse Mogawane as he made his way around the final bend in the second leg of the race. Mogawane fell and clutched at his left shoulder as the baton rolled away.
Set to run next in the relay, Pistorius stared at the scene in disbelief. He put his hands on his head and began walking off the track, figuring his time in London was done.
In the span of two hours, after word of the successful appeal, Pistorius went from crestfallen to celebrating. On Twitter, he wrote: "IT'S ON!! We in the FINAL."
"Will be up on the 3rd leg tomorrow for the Final! Really can't wait!" Pistorius tweeted, adding "Emotional roller coaster!"
Pistorius did not get a chance to run in the final when South Africa earned a silver medal in the 4x400 relay at last year's world championships — although he did earn a medal by virtue of having run in a preliminary heat.
On Thursday, Kenya was disqualified from the competition when the referee ruled Vincent Mumo Kiilu cut across too soon and caused Mogawane to fall. Kiilu had a spike mark on the back of his right shoe. Mogawane dislocated his shoulder.
Track and field's governing body said Pistorius' team will run in Lane 9, on the far outside of the track, after the jury met and "agreed to advance the South African team, even though they did not finish the race, considering that they had been severely damaged in the incident with Kenya."
Originally, three teams from the two heats were supposed to advance to the final, along with the teams with the next two fastest times. Lane 9 was going to be empty. The United States, Britain, Bahamas and Trinidad and Tobago were among the other qualifiers.
A decathlete from South Africa, Willem Coertzen, was competing and glanced up after Mogawane hit the track, but wasn't aware of South Africa's inclusion in the relay final until after he had finished pole-vaulting.
"I'm ecstatic," Coertzen said. "I haven't seen it happen before like that — could be something new — but I'm excited for them. After everything that (Pistorius) has been through, good luck to him."
This was quite a day for Pistorius.
Quite an Olympics, too.
After a long fight to be allowed to compete in the Olympics, Pistorius ran in the 400 metres and finished second in his opening heat, then was last in his semifinal.
Last week, the IAAF announced he could run any part of the 4x400 relay at the Olympics, not just the opening leg when runners have to remain in their assigned lanes for a lap.
"This whole experience was one of the highlights of my career," Pistorius said. "I just had the most amazing experience representing my country. My experience here, everything has been superb. From the organization to the crowd to the fans and to friends. I couldn't have hoped for a better time."
Pistorius was born without fibulas and his legs were amputated below the knee before he was a year old.
"Oscar knew growing up that he was different," his father, Henk, told The Associated Press. "But he knew in competition with his friends, which we always encouraged, that he was differently abled. So we don't talk about a disability. We speak about what is your different ability?
"Of course it makes me proud (watching him). ... Oscar is on the world stage and is a celebrity."
AP Sports Writers Gerald Imray and John Pye contributed to this report.