Meeting the Blade Runner
For a man at the centre of the biggest story of these World Championships so far, Oscar Pistorius cuts a discreet and relaxed figure.
Dressed in black tracksuit bottoms and t-shirt, his signature Cheetah blades replaced by gleaming white trainers, he is sitting in a cafe opposite the athletes' village in Daegu, indistinguishable from any other tanned young sportsman whiling away the empty hours pre-competition.
Appearances can be deceptive. While Usain Bolt may appear on more billboards around town, it is the inclusion of multiple Paralympic gold medallist Pistorius on the start-lists that has commanded more column inches.
Thanks to a controversial ruling from the Court for Arbitration in Sport and a massive personal best a few weeks ago, Pistorius will line up in Sunday's 400m heats as the first amputee athlete to ever compete in an athletics World Championships.
To some it is an inspirational tale of courage against adversity, to others a PR-driven story in which science and ethics have taken a back seat to emotion and hype.
To the man himself, it is something far less complicated: a simple desire to run as fast as he can, against the fastest there are.
"I think I've always regarded myself just as an athlete," he says. "I'm very proud to be a Paralympian, but even Paralympic athletes are athletes just like anyone else.
"I consider myself an athlete, just a 400m specialist. When I line up I'm not going to think how great it is to be here, I'll think about how hard I'll have to work to get to the end in a time I'll be happy with.
"It's not any different from any other race. It's a great honour to be here, and this is one of the top competitions that any athlete will have the pleasure of participating in their career. But I don't run to get to a point where I've decided [appearing at the Worlds] is an accomplishment."
The journey to Daegu has been a long one for the 24-year-old from Pretoria. When he first tried to compete in IAAF events he found himself excluded by a new clause added to the sport's governing body's rule 144.2, which relates to the use of "technical aids" during competition.
Clause (e) prohibited the "use of any technical device that incorporates springs, wheels or any other element that provides the user with an advantage over another athlete not using such a device."
A study carried out by Professor Peter Brüggemann at the German Sport University in Cologne had indicated that Pistorius's carbon-fibre blades enabled him to run at the same speed as able-bodied sprinters with about 25% less energy expenditure. Pistorius and his coach Ampie Louw disagreed, appealed to CAS and won.
That was three years ago. The battle since then has been against a foe familiar to all track athletes, the clock. At the last Olympics Pistorius was 0.7 seconds off the qualifying time. Even at the start of this year he appeared to be well off the pace.
If his PB in Italy was a clear 0.18 seconds inside the Worlds qualifying mark, it was also a full half a second inside his previous best. As improvements go, it was massive.
"I've noticed a difference in attitude from my fellow competitors, because I think they respect me more," says Pistorius. "I spoke to a friend the other day who's a really well known 400m athlete. He was saying I look like I've lost weight. If anything I get treated just like any of the other guys."
That PB was also just the 18th fastest time in the world this year. On that basis, Pistorius could struggle to get anywhere near Tuesday's 400m final. So, after such a struggle to be allowed even to enter, what would now constitute success?
"There are probably two parts," he says. "One would be making it through the first and second round, trying to make the semi-final, and I think that's a realistic goal.
"The other one would be to gain as much experience as I possibly can for the London Olympics next year. This is a phenomenal chance to go through the same kind of pressure and competition as next year."
Pistorius is not the first Paralympic athlete to compete in world-class able-bodied events. His compatriot Natalie du Toit swam the open-water 10k at the last Olympics, while USA's Marla Runyan, who is legally blind, finished 10th in the 1500m at the 1999 Worlds in Seville.
Ireland's Jason Smyth, the double Paralympic champion who is also visually impaired, lined up in the 100m heats here in Daegu on Saturday evening.
But amputee Du Toit competes without a prosthetic limb, Runyan and Smyth without guides. It is Pistorius's blades which take athletics into unexplored areas, those distinctive "upside-down question-marks", as he describes them, the punctuation in a debate that can get extremely heated.
South African sports scientist Ross Tucker accepts that Pistorius is an inspiration to millions. He also thinks the scientific case is closed: Pistorius's carbon-fibre blades give him a significant advantage.
"Biomechanical studies have found that he is able to accelerate his limbs at speeds that are off the biological charts," he told the BBC.
"In sprinting one of the key things is that you have to be able to move your limbs quickly, and Pistorius can do this many, many milliseconds faster than any other athlete in history - even faster than Usain Bolt in the 100m.
"There is such an impenetrable wall of PR support for Pistorius now that for a federation to take him on and say, no, you're not allowed to run, is a PR disaster. They would be accused of discriminating against him just because he's now a success.
"But every single study so far shows the same thing, which is that there is this performance advantage as a result of the energy enhancements and the reduced mass of those limbs."
Saeed Zahedi is a biomechanist who has been at the forefront of prosthetic design for the past three decades.
"Oscar has to have his stump inside a socket, and he has to compensate all the forces around his stump," he told the BBC. "Essentially the sense of fatigue that comes from the act of compensation is a lot higher in Oscar's case than for any ordinary runner."
Richard Whitehead, the Briton who holds the double-amputee world marathon record, agrees. "Wearing prosthetic limbs, you have lactic build-up in other parts of your body. When Oscar finishes he is physically exhausted - in the race when he qualified for the Worlds, he collapsed at the finish because he was so exhausted.
"Athletes, as well as people in general, are inspired by someone doing something positive - and that's what Oscar is. He's been given a gift to participate at the highest level, he wants to push the barriers, and he has a right. As long as he qualifies like everyone else, I don't see why he shouldn't be allowed to compete in Daegu."
Has Pistorius heard any whispers from within the athletes' village?
"No, no, nothing like that. At this level we don't look at our opposition and criticise them when we don't do well. We look at ourselves.
"If you don't run a good race, you can't point fingers and anyone else. I've got a lot of respect for the guys I participate against. They know how hard I train and how much I sacrifice for the sport.
"You'll always have one or two guys that differ, are ill-informed and like controversy. There's nothing I can do about that.
"I'm very confident. There's no way the prosthetic leg can provide any advantage."