Robert Dean (22), Brogan Anderson (23) and Manu Panirau (24), of Team Hammerhead, combine with Australian-based New Zealander Joe Muir to compete in a 16-man light-heavyweight elimination tournament. The winner will pocket $10,000.
Hammerhead coach Matt Toa said he was confident his fighters would do well, but winning was not the sole focus.
"The opportunity for our boys to gain some international experience and showcase their skills in front of thousands of people will be a huge asset to them now and in the future," Toa said.
The tournament was structured so team-mates would avoid fighting each other unless there was no other option, such as in a semifinal or final, Toa said.
"It is something we have discussed as a team and it would be one of the hardest things these boys would have to face, but if it happens, they will handle it."
South Africa will have eight fighters competing and Australia four.
International Sport Karate Association is the sanctioning body that governs shows in New Zealand and Australia.
Its New Zealand supervisor, Wahid Wennekes, said ISKA Australasia was asked by the South African Government and promoter Craig Mayman to set up rules and choose competitors for the tournament.
It was not possible for ISKA to sanction an event in South Africa, so it would be officiated by the Government.
Future tournaments held in Australia and New Zealand would be sanctioned, and both host countries would then have eight fighters competing, Wennekes said.
The Netherlands-raised 44-year-old, who competed in 99 professional kickboxing fights and held several European titles, said he chose the three Dunedin fighters because they had the ability and potential to have a long future in the sport.
For a fighter to be crowned champion, he will have to win four fights lasting varying lengths. The first two are scheduled for three two-minute rounds and the semifinals and final are scheduled for four two-minute rounds.
There will be a 30sec limit on grappling, unless a submission seems likely.
Flights and accommodation for the competitors, and the prize money, will be paid for by Mayman.
The New Zealand contingent will arrive in Johannesburg on September 25 and the tournament starts three days later.
The side was initially going to be made up of fighters from Team Hammerhead and Strikeforce, a national mixed martial arts club. Toa said Strikeforce coach Karl Webber withdrew himself and his team for "personal reasons", which he understood.
Toa has had to pull out of his Industry of Combat New Zealand heavyweight title rematch with Steven Warby in Auckland later this month.
He said it was not an easy decision but he hoped to fight Warby again, either at an ICNZ show or at one of Hammerhead's Dunedin events, but his main priority had to be the welfare of his fighters.
