Former New Zealand triathlete Simone Ackermann will represent South Africa after claiming to have been "misled" and "treated unfairly" by the governing body in the past year.
The 27-year-old had been part of Triathlon New Zealand's high performance squad, but activated dual citizenship to pursue her Olympic dream.
Ackermann will compete under the International Triathlon Union flag for now but, under their rules, could compete for South Africa after a year if both national federations agree.
The East London-born athlete has competed in five world series Olympic distance events since the start of 2016, finishing between 19th and 27th.
She had "wrestled" with the decision to change allegiance, but one factor was compelling.
"My non-selection for the Olympic Games was the catalyst for this change.
The decisions and actions of Triathlon New Zealand recently, though, finalised my decision.
"When you feel you have been treated unfairly, it is tricky to know how much to say. Say too much, you could be perceived as a trouble-maker or bitter. Say too little, you look like a doormat.
"I believe those making the selection decisions within Triathlon New Zealand misled me. I was led to believe that it was important for there to be three females at the Olympic Games [New Zealand had qualified three] and that I had to secure the third spot."
TriNZ's qualifying standards meant two top-eight world series finishes across the designated period was the minimum requirement, barring extenuating circumstances like recovery from injury, or agreeing to work as a domestique.
The New Zealand Olympic Committee ultimately decided which athletes went to Rio and only two Kiwi women made the cut.
"When New Zealand forfeited their spot, the position rolled down to the next ranked athlete on the Olympic rankings points list. This was a Russian.
"Given what the McLaren report had found [with systemic doping], it was insulting that those involved would rather give an Olympic spot to a Russian athlete than one of their own.
"This illustrated that they did not have any faith in me. Put simply, if you believe in an athlete you give them a chance."
Before the Olympic selection, former high performance director Graeme Maw said: "The selectors can consider a place for a team role, which would become part of an athlete's terms for selection rather than picking somebody and then negotiating."
Ackermann needed discretion to get picked.
Maw declined to speak on the issue yesterday and TriNZ chief executive Claire Beard, who has been in the role since February, could not be reached for comment.
The governing body is undergoing extensive changes after their annual high performance funding dropped from $1.25 million to $750,000 in December. Several staff have left post-Rio, such as Maw and coaches Tim Brazier and Jon Brown. Mark Elliott has returned as high performance director.
Ackermann suggested swapping allegiances gives her the best chance of attending the Tokyo Games.
Only one South African woman - 30-year-old Mari Rabie (23rd) - was ahead of Ackermann (42nd) in the 2016 world rankings. "It came to the point where I think I had lost faith in Triathlon New Zealand, and I felt they did not have faith in me."
Her next major race is expected to be at Yokohama in mid-May.