"I'm sorry," she said. "I think this is the first time I've ever cried after a swim because it means so much. It's something that I've wanted to do for my whole life and I am just really, really happy."

	Beijing bound: Natalie Du Toit has qualified for the Olympics

A few minutes earlier, Du Toit had touched home in fourth place in the 10km at the World Open-Water Swimming Championships, comfortably inside the top-10 finish required to qualify for the Olympic Games in Beijing this summer. But as the 50 competitors emerged from the murky water after their two-hour ordeal, the fact that Du Toit remained on the pontoon by the finish was the clue that this was no ordinary story.

It was not until a member of her South African support team arrived with her prosthetic leg that the 24-year-old was able to join her rivals on the weary trudge back to dry land. Astonishingly, she can now look forward to lining up alongside the world's greatest long-distance swimmers in Beijing, despite the fact that her left leg was amputated above the knee seven years ago after she was knocked off her motor scooter.

She has made history by becoming the first amputee to qualify for the Olympic Games, an achievement that defies scientific logic. While lawyers still argue over whether her compatriot, Oscar Pistorius, gains an unfair advantage on the track over his able-bodied rivals through his prosthetic blades, Du Toit's incredible feat is to have finished fourth in a two-hour race in choppy water, and with swimmers bumping and boring into each other, with only half the leg-propulsion of her rivals.

Unlike Pistorius, Du Toit does not wear a prosthetic leg in races and is therefore free to compete in Beijing. It is akin to competing in a sculling race with one scull or a kayak race with a single-bladed paddle. Her secret? Well, there is no secret, she says, no physical or technical trick to compensate for the loss of a limb. Just hard work and obsessive determination. "There's no real compensation. You just do the hours in the swimming pool, you do the hours of racing and you do the hours of mental preparation. You just go out and give it everything. I don't even think of one leg, two legs. When you're racing in an able-bodied competition you're all equal and you go out there and try your best, and that's what counts.

"Swimming is my passion and something that I love. Going out there in the water, it feels as if there's nothing wrong with me. I go out there and train as hard as anybody else. I have the same dreams, the same goals. It doesn't matter if you look different. You're still the same as everybody else because you have the same dream."

The open-water event will be making its Olympic debut in China and Du Toit's presence in the starting line-up is guaranteed to be one of the stories of the Games.

At the age of 16, and with her left leg still intact, she narrowly missed qualification for the 2000 Sydney Olympics, but her accident a year later, when she was hit by a car as she returned home from a training session, looked to have ended her career. Yet only a year later she became the first disabled swimmer to compete in an able-bodied event when she raced for South Africa at the 2002 Commonwealth Games. In 2004 she failed in an attempt to qualify for the Athens Olympics but went to the Paralympics instead and won five gold medals. But still the Olympic dream burned within her.

"I think for me it's about having the dream of going to the Olympics all my life. I've dreamed about it since I was six years old and I started swimming, and then when I just missed out on qualifying for Sydney. After the motorbike accident it was just a matter of going out there and seeing what I could do, but back then I could never have dreamed this day would come. Definitely not. For the first five years after my accident I improved a lotbut then I didn't improve much at all. To come out here and have such a good race is fantastic."

Britain's Cassie Patten was also celebrating after she finished second behind Russia's Larisa Ilchenko in a repeat of last year's World Championships in Melbourne, while fellow Briton Keri-Anne Payne also made sure of her Olympic place in eighth position.

It is clearly not an event for the squeamish. Patten, who has suffered from seasickness and jellyfish stings in previous races, encountered a new problem in a stretch of water normally reserved for rowing and canoeing. "On the last lap I tasted something very much like duck poo," she said. "Not that I've eaten duck poo before, but it didn't taste or smell very nice."

Patten is a serious medal prospect in China, perhaps even a golden one, though she was happy to be upstaged by the achievement of her South African rival yesterday.

"Natalie is an outstanding swimmer - very, very strong not only physically but mentally," said Patten. "For someone to overcome such an horrific accident and then qualify for the hardest swimming event there is, that's quite outstanding."