Wayde van Niekerk said he's given clean athletes a boost with his blistering 400m world record -- and admitted that even he didn't believe such a time was possible without drugs.

The South African produced a run for the ages at the Rio Olympics, when he tore round the outside lane to smash Michael Johnson's hallowed, 17-year-old mark.

Athletics' battered reputation means every record attracts questions about drugs, but van Niekerk said his performances showed could what be accomplished clean.

"I think it could be a good testimony to other athletes who want to play the game clean," he told AFP.

"I thought you had to use something to run a sub-44, and look where I am today. And I've done it clean and I've done it simply by pure hard work and dedication. 

"If I can be a testimony, I think anyone else can do it, if I could be an example for that," he said in an interview at the Visa Everywhere Lounge at Copacabana beach.

Track and field had a torrid build-up to the Rio Games, with Russia's team suspended en masse after revelations of a state-backed doping conspiracy.

Van Niekerk's record has been on the cards after this year he became the first athlete to go sub-10sec in the 100m, sub-20 sec in the 200m and sub-44sec in the 400m.

He said he was inspired by a motivational talk from Usain Bolt whilst training this year in Jamaica, when the sprint king urged him to grasp his opportunities.

"That's why I go out there as hard as I can because I don't want to let go of opportunities now I'm in the shape that I am in," he said. 

"I'm really taking that advice that he gave me and using every single chance I get on the track to better myself."

However, the 24-year-old had no sense that he was about to beat Johnson's 1999 record of 43.18sec, despite a bold prediction from Bolt that he was about to make history.

- Super gran -

"I really just went out there to try and repeat what I did last year," said van Niekerk, who became world champion over 400m last year in Beijing.

"Obviously I would have loved to improve myself but world-record improve myself? I definitely didn't think I could do it and it's really been a blessing."

He added: "(Bolt) came to me after the race and told me, 'I told you you could do it!' It's really a special moment.

"A few months prior to the Olympics we spoke about it and he told me I can (break the record). Obviously it did help me believe in myself... yeah, I'm grateful for the belief that he had in me."

Van Niekerk's unusal training set-up sees him coached by Tannie Ans, a 74-year-old great-grandmother who mainly looks after university-level athletes.

Ans's training sessions are unpredictable and can include football kick-abouts. "Not even I can explain what she's doing," he said.

"She loves being involved in a lot of different areas but I think at the age she's at now I'd love to see her take it easy and just focus on herself," he said. 

"But I think that's what keeps her going and that's what makes her smile every day and I believe with her always being busy that's how she comes up with the new ideas every day."

Next up is a potential 300m showdown with Bolt, a tantalising and left-field possibility raised by the Jamaican.

"I wouldn't go out there and say 'Usain Bolt, I want to challenge you' but obviously being able to race against a great like Usain Bolt would give me a lot of motivation," van Niekerk said. 

"I always try to put out my A-game, especially if it was against someone as good as him. But I'd be honoured even to take a victory walk with around the track."

Source: AFP