South Africa’s Wayde van Niekerk celebrates winning the men’s 400-meter final Sunday night. (AFP PHOTO/JOHANNES EISELE)

The most unbelievable race of the 2016 Olympics had an unbelievable woman behind it. And she wasn’t even on the track.

South Africa’s Wayde van Niekerk stunned everyone when he convincingly won the 400-meter race from Lane 8, a blind position, and shattered Michael Johnson’s 17-year-old world record in the process. His winning time was 43.03, made even more unbelievable considering he hadn’t ran faster than 44.11 this year.

Shortly after van Niekerk beyond impressive performance, the story of his unconventional coaching spread. An Olympian with a 74-year-old great grandmother as his coach certainly is a new one.

Ans Botha was once a sprinter and a long jumper, and her pupils call her “Tannie Ans,” meaning Auntie. Last year, the head coach at South Africa’s University of the Free State told the City Press that her “passion is too high” to stop coaching in a career spanning five decades. She got emotional when describing her responsibility in coaching van Niekerk.

“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 told the City Press.

Botha started coaching van Niekerk in 2012, connecting after he attended the University of the Free State as a marketing student. They met with his parents and laid out a plan, the focus of which was to not push van Niekerk’s body beyond its limits. Their first three months in partnership were spent rehabbing some nagging injuries.

The strategy worked — since she’s been his coach, van Niekerk’s time has dropped by a whopping four seconds.

Still, Botha was relatively inexperienced. Before teaming up with van Niekerk, her top international achievement constituted Thuso Mpuang’s silver (2011) and bronze medals (2009) from the World Student Games. When van Niekerk won last year’s world championships in Beijing with a winning time of 43.48 seconds, that was Botha’s first time at an IAAF world championships.

But the great-grandmother of four had the wisdom not to be intimidated.

“I only stole [coaching ideas] with my eyes. That is, if I see something that will work on my athletes, I will try it and implement it,” she told the City Press in 2015. “That’s how I always try to bring something new in our training. They have to enjoy training; that’s very important. They say you’re never too old to learn, especially in athletics.”

You’re apparently never too old to coach someone to a new world record either.