Radford leads the men's series and has confirmed he will be swimming despite recent surgery for appendicitis.
The illness forced him to miss the last round, the State Sand to Surf, and the recent pool nationals in Auckland.
Radford heads into the series finale with a narrow lead over Auckland's Phillip Ryan, but with points from just three of the six races counting, and double points on offer in the King of the Bays, the final standings are set to be markedly different to what the currently are.
For example, if Australia's double open water Olympian Ky Hurst wins the State King of The Bays, he will secure the maximum 400.00 series points, and leap frog everyone to win the $20,000. If he wins, Hurst has made a big promise.
"The money will go into a bank account that I'll be opening for my 4-month old son," he said.
The same scenario is playing out in the women's series as well. Former world 5km open water champion Australian Melissa Gorman is currently in just sixth place.
But if she wins, the double Olympian and former Commonwealth Games medallist will also overtake all her contenders and successfully defend the series title she won last year.
"The motivation of winning that money is massive," she said. "$20,000 will make such a difference and help me out a lot with my training and overseas travel plans, so I'd love to have a good race this weekend."
In all 1600 swimmers will take to the water on Saturday, in the race's 10th anniversary.
Current standings (After five rounds):
Men:
Kane Radford (Rotorua) 298.28
Phillip Ryan (Auckland) 296.86
Casey Glover (Wellington) 287.87
Ky Hurst (Queensland) 200.00
Codie Grimsey (Queensland) 197.89
Women:
Charlotte Webby (New Plymouth) 299.57
Cara Baker (Auckland) 297.52
Kirsty Wannan (Auckland) 285.40
Natalie Woodgate (Auckland) 274.10
Bridget Maher (Auckland) 273.42
Melissa Gorman (Queensland) 200.00