South African sprinter Wayde van Niekerk stunned the Olympic Stadium tonight as he smashed the 400m world record.
The 24-year-old Cape Town runner gave a blistering performance from lane eight with a time of 43.03 - breaking US star Michael Johnson's 19-year record.
And four time Olympic gold medallist Johnson, watching from the BBC commentary box, was one of the first to congratulate him - saying: 'Oh my God! From lane eight, a world record.
'He took it out so quick. I have never seen anything from 200m to 400m like that.
'He may well have run faster in the second 200m, than in the first.
'Well done to this youngster. A world record. That was a massacre from Wayde van Niekerk. He just put those guys away.
'Van Niekerk is so young, what else can he do? Can he go under 43 seconds? It is something I thought I could do, but never did. Usain Bolt will be retiring soon, this could be the next star of the sport.
Unstoppable: South African sprinter Wayde van Niekerk wrote his name into the record books tonight as he smashed the 400m world record
But while the crowd packed inside the stadium chanting the name of their new hero, his biggest fan was among them - a 74-year-old great grandmother, who is also his coach.
Ans Botha, exactly half a century his senior, is van Niekerk's coach - and has guided him through to Olympic glory.
‘They are exceptionally close, very connected, very trusting and respect each other enormously,’ explained DB Prinsloo who has worked alongside Mrs Botha for 25 years at the University of the Free State.
Known affectionately as ‘Tannie Ans’ to her athletes – Tannie meaning Auntie in her first language Afrikaans – has given Van Niekerk ‘a positive and protective environment to train in’, Mr Prinsloo told MailOnline.
‘But she doesn’t put up with any nonsense from any of them. She has rules, standards and is very much into the discipline of training and competing.
'Tannie Ans has a strict regime and every one has to respect that.
'Wayde knows where he stands with her, he acknowledges her experience and skills and takes advantage of all the wisdom she has to offer,’ he added.
Mrs Botha’s positive impact on Van Niekerk’s performance since they began working together three years ago has been dramatic.
The lean runner, who is from Cape Town, has knocked four seconds off his 400m times to a now world-leading sub-44 second mark.
Bond: The unique partnership between the van Niekerk, 24, and Ans Botha – exactly half a century his senior - has delivered extraordinary career highlights for both athlete and trainer
Winner: van Niekerk lit up the Maracana on Friday where he smashed the 19-year world record
Stunning: He shocked observers by not only winning gold and breaking the world record but doing so from lane eight, which some have said is the toughest lane to achieve it
Mrs Botha’s positive impact on Van Niekerk’s performance since they began working together three years ago has been dramatic
His performance at last year’s Beijing World Championships is ranked the fourth-fastest in history, three-hundredths of a second off Michael Johnson’s record of 43.18
Mrs Botha’s trip to China was her first time at an IAAF World Championship.
But rather than being star-struck by super stars such as Usain Bolt, she said she learned from them – and even stole some coaching ideas.
‘If I see something that will work on my athletes, I will try it and implement it. That’s how I always try to bring something new in our training.
'They say you’re never too old to learn, especially in athletics,’ she told South Africa’s City Press newspaper.
Mrs Botha’s (far right) trip to China was her first time at an IAAF World Championship
Rather than being star-struck by super stars such as Usain Bolt, she said she learned from them – and even stole some coaching ideas
Originally from the country now known as Namibia, Mrs Botha began coaching in the 1960s, initially just her own talented children, but then began being sought out by other rising stars. The idea of retiring doesn’t even cross her mind.
‘I’m very blessed because I don’t have any health problems, and it is because I’m busy with young people – and you have to be high up there with them,’ the widow said. ‘My passion is too high to even think about that.’
And she doesn’t take her duties towards her young protégée lightly.
‘I wouldn’t say I’m afraid ... but I have such a big responsibility to get this athlete to develop to his full potential.
'Also, I need to try to do my very best not to do something wrong that might break him,’ she said.
South Africa’s Wayde van Niekerk cruised easily into the final at the Olympic Statdium and was quick to pay tribute to the white-haired coach who helped him get there
Her principle guide is ‘listening to what his body says to us – if the body says stop, we stop, or go a little softer,’ she added.
Van Niekerk, who was the flag bearer for South Africa at the Games’ opening ceremony, has flown ten members of his family to Rio to watch him compete, including his girlfriend Chesney Campbell, 24, his grandparents and parents, Odessa and Wayne.
Van Niekerk is the first athlete to have run 100m in under 10 seconds, the 200m in under 20 seconds and the 400m under 44 seconds. He will begin tonight’s race in lane 8.