By SABC Sport
5th January 2024
The 32-year-old has developed into one of the best players in the world, but he has also become an ambassador for South Africa, as well as rugby in general, and Nienaber reckons it is his enduring authenticity as a person that has been key to his ongoing success.
Kolisi is arguably the sport's most recognisable face after leading the Boks to successive Rugby World Cup titles in 2019 and 2023.
When the flanker took on the leadership role in 2018, he became the country's first black captain and, as it has transpired, their most successful one too.
Nienaber has been a huge part of Kolisi's career having first coached him when the forward was a teenager, watching with interest and pride at how the back-rower has grown as both a player and a man.
"Siya I started coaching when he was 19 in the Western Province academy," the former Springbok head coach told The Good, The Bad and The Rugby podcast.
"Siya hasn't changed, he never became the title. Siya is Siya Kolisi and then you get Siya the Springbok rugby player and the World Cup-winning captain.
"Siya never became Siya the Springbok World Cup-winning captain, he always stayed Siya."
Nienaber has since parted ways with SA Rugby, leaving his role as South Africa's head coach after the World Cup to work under Leo Cullen at Leinster.
It means that the 51-year-old will never work with this particular group of players again, but it is a time in his life that the defence guru will remember forever.
The ex-Munster and Stormers coach especially heaped praise on number eight Duane Vermeulen, but also spoke about how the team as a whole remained humble.
"You ask, what's the best? What's the thing I will always remember and cherish the most? It's that the players never became their titles.
"I've been working with Duane Vermeulen since 2006, 17 years we've been working together, and Duane just stayed Duane. He stayed the guy that came from the Pumas to the Cheetahs, he always stayed that guy.
"The nice thing is that I saw them when they were young; they were naughty, they weren't married, and then I saw them get married and become husbands to wives and fathers to kids.
"To see the growth of the players is probably the thing that will sit in my head when I'm old, grey and shaking in front of the fire - I will remember that."