- Olympic 400m champion Wayde van Niekerk trained by 74-year-old veteran coach
- Coach Anna Botha switched his focus to 400m from 200m
- Van Niekerk says she's an "amazing woman"
- Pair work together at the University of the Free State
(CNN)She's a 74-year-old veteran coach, whose philosophy is you're never too old to learn.
South Africa's Wayde van Niekerk sensationally won Olympic 400-meter gold at Rio 2016 -- smashing Michael Johnson's 17-year-old record along the way -- and he has his coach Anna Botha to thank.
The 74-year-old coach's philosophy is all about discipline and hard work, albeit leavened by laughter.
"You are never too old to learn," Botha -- a great-grandmother of four with a neat wave of white hair -- told the IAAF website of her coaching convictions -- and that's the principle she applied to turning Van Niekerk into an Olympic champion.
The 24-year-old started working with Botha after the last Olympic cycle in 2012 when he began his studies at the University of the Free State in Bloemfontein. She's been the head coach of track and field there since 1990.
A former sprinter and long jumper, Botha immediately set about switching his focus from the 200m to 400m to protect him against persistent injuries, and the times steadily began to tumble.
In 2013, Van Niekerk's best time over the one-lap sprint was 45.09 seconds; when he won his first major medal at the 2015 World Championships it had dropped to 43.48; and in Brazil, he shattered Johnson's world record in a stunning 43.03s.
Van Niekerk credited Botha's regime on Fox Sports after his win: "She's really kept me very disciplined on the goal and where I need to be.
"I'm really grateful I can go on the track and say my coach has pushed me to reach every level and believe anything is possible.
"She's an amazing woman. She's played a huge role in what I am today."
Botha, who is affectionately called 'Tannie Ans' by her athletes, began her coaching career training her daughter Herma in her homeland of Namibia, but soon had a growing brood of athletes.
Her family moved to Bloemfontein in the late 1980s and it was there her coaching career went from strength to strength. Botha regards the secret to her success as praying, "because I am unable to do it on my own."
There may be 50 years between them but Van Niekerk and Botha have found a partnership of personalities that works.
"I dearly love all my athletes but it's about being strict," explained Botha, who also believes female coaches can offer "something different psychologically."
She added: "We can laugh, but when we have to work hard, we work hard."
Botha was sat in the stands at Rio's Olympic Stadium to watch her star pupil lead from the gun to the line, running blind in the outside lane eight, to win his first Olympic medal.
"I thought someone was going to catch me, because I felt very alone and I was like 'what's going on, what's going on?'" Van Niekerk told reporters in Rio. "It gave me so much motivation to keep pushing.
"I believe in myself as an athlete and I believe in my abilities," he added. "God just showed how faithful he's been in my life and I'm very grateful for the continuous blessing."
The 24-year-old ran his own remarkable race in Rio and maybe that's because great-grandma knows best.