The dashing blade Oscar, accidental track hero

Simon Turnbull meets Oscar Pistorius, the South African sensation hoping to add London Olympic glory to the Paralympic gold medals he won in Athens and Beijing

It all might have been very different for Oscar Pistorius. As a 16-year-old he was happy enough with his sporting lot as a schoolboy rugby player with Pretoria Boys' High, charging about the place breaking all convention – even when an opposition player in a match in Johannesburg tackled him so hard one of his prosthetic legs came off. It failed to stop him. He hopped over the tryline to score.

But then came the day, in June 2003, when young Oscar was slammed and dunked by a couple of brutish teenage giants. It left him with a busted left knee.

He thought his sporting days were over. He never played rugby again but the very next summer he was standing on top of the medal rostrum at the Olympic Stadium in Athens with a Paralympic gold medal around his neck.

Oscar Pistorius is many things: the Blade Runner, the fastest man on no legs, a barrier-breaking inspiration of a 25-year-old. At the Olympic Games which open in London in 104 days' time, barring injury and a dramatic loss of form, he will become the first amputee to compete in the greatest sporting show on earth. Yet he is an accidental hero.

Pistorius would never have become a track athlete had he not damaged his knee so badly that he had to quit rugby. It was as part of his rehabilitation that he was given medical advice to do some sprint training. He was told it would be the best way to regain functionality in the knee joint.

"It was all very accidental," Pistorius says, chuckling at the thought of what might not have been. "It was only eight months after I started doing some sprint training that I went to Athens for the Paralympics in 2004. Even then, when I was in Athens, I wasn't really planning to continue with athletics.

"The following year was my final year at boarding school and in the end I thought, 'I'll just keep doing athletics while I finish my schooling'. It wasn't until 2007 or 2008 that I decided to start to take it a lot more seriously."

So might the sensation of the track-and-field scene – the remarkable young man who was born with no fibulae and who had both legs amputated below the knee at the age of 11 months – have blazed a groundbreaking trail as a Springbok instead? "I don't think that I would have been a decent rugby player," Pistorius says. "I played decent school rugby but I wouldn't have done anything phenomenal down that path."

Having taken an inadvertent turn down the athletics path, the highly personable, endearingly self-effacing Pistorius is just one step away from becoming an Olympic phenomenon. He needs one more 400m run inside the 'A' standard qualifying time of 45.20sec to secure his place at London 2012.

In June last year he clocked 45.07sec at Lignano in Italy, but only times in 2012 will be considered. Last month he ran 45.20sec at a meeting in Pretoria but he has been asked to produce a second sub-45.30sec performance in 2012 – and on the international circuit, closer to the Games.

Pistorius's times at the South African Championships, which opened in Port Elizabeth yesterday, will not be considered. It is just as well. It was blowing a gale when he ran in his heat and semi-final yesterday, clocking 48.24sec in the former and 47.91sec in the latter to qualify for today's final. "I don't like running in Port Elizabeth," he confesses. "Nobody does. It's a bit like Aberdeen. It's miserable and there's a lot of wind. I ran in Falkirk one year and there was an 8.3 metre-per-second wind. Running down the home straight, at one stage I was in danger of going backwards. It was unbelievable."

To many, it is barely believable that someone confronted with the kind of obstacles Pistorius has faced in his life can be so close to making an Olympic Games. That he has surmounted so many hurdles is due in large part to the enduring influence of his mother.

Sadly, Sheila Pistorius will not be around to see her son compete in the London Olympics and Paralympics. She died in 2002. It was her stridently positive attitude that caused her son to see his disability as anything but a handicap.

"She was very hard-headed, I think, and very determined," Pistorius reflects. "There wasn't much scope for me to think about my disability as a disadvantage or to pity myself. She's definitely a huge reason why I've got the drive that I have, and why I have been able to achieve the things that I have."

That drive was evident when the world governing body of track and field, the International Association of Athletics Federations, ruled in 2008 that the prosthetics Pistorius uses when he races – the J-shaped carbon fibre blades called Flex-Foot Cheetah – gave him an unfair advantage over his rivals. Pistorius and his long-time manager Peet van Zyl took the matter to the Court of Arbitration for Sport and won.

Last summer Pistorius became the first amputee to compete in the IAAF's biennial World Championships, making the finals of the individual 400m. He also earned a silver medal in the 4x400m relay but the fact he was dropped from the South African team for the final left a bitter taste that still lingers. "I'm still a bit heartbroken about it," Pistorius confides. "Whatever their reasons were, I still don't know what they were thinking. They didn't select the best team for the final. They ran half a second slower in the final than we did in the semi. We broke a national record. We ran sub three minutes, which is a huge accomplishment."

Pistorius and his manager were not the only ones stunned by the decision of the South African team management. It left Michael Johnson dumbfounded. "It doesn't make sense to me at all," the 400m world record-holder said. "I can't imagine a scenario where you would not want him in your relay. You've got to question the selectors."

"Michael's a really smart guy," Pistorius says. "When you've got an athlete who's chosen to represent his country in the individual event and he's not even participating in the final in the relay it doesn't really make much sense."

The composition of the South African 4x400m relay team in London is going to be interesting. First, though, the Blade Runner has the 400m final at his national championships today. On 22 May he will be in Manchester, for the BT Paralympic World Cup 100m and 200m, before chasing his second Olympic 400m qualifying time on the Diamond League and European circuit.

The South African phenomenon has good friends on the British team – Martyn Rooney and Dai Greene were guests at his house on New Year's Eve.

"I love coming to London," Pistorius says. "The closer we get to the Games, every time I land at Heathrow I get more and more goosebumps and butterflies. It feels like a very realistic experience coming up."

Oscar Pistorius is a member of Team Ossur, a global leader in non-invasive orthopaedics that help people live a life without limitations. www.ossur.co.uk