Russian whistleblower Yuliya Stepanova will not appeal to the Court of Arbitation for Sport (CAS) over her ban from running as an independent athlete at the Olympic Games in Rio.
Stepanova's evidence helped expose state-backed doping in Russian sport and she has since fled the country.
The 800m runner had been ruled out when the International Olympic Committee (IOC) banned from Rio any Russian who had previously served a doping ban.
Stepanova's hopes of competing were raised on Thursday when CAS said that ban was "unenforceable" but the 30-year-old will not make a late appeal in order to compete.
She participated in last month's European Athletics Championships in Amsterdam as an independent athlete.
"We are disappointed that the IOC turned a blind eye to the risks Yuliya had to take, and the damage to her athletic career, to expose the systematic cheating in Russia and live up to the ideals expressed in the World Anti-Doping Code," Stepanova and husband Vitaly said in a statement.
"For her to be called 'not ethical enough for the Games' in the media release of the IOC on July 24 is a tremendous blow.
"We believe that in exercising this discretion to deny Yuliya a place in the competition, it sends a message that the World Anti-Doping Code and the values of Olympism are merely words on a page. As a result, we will not file an appeal to CAS."
That means US-based long-jumper Darya Klishina will be the only Russian athletics participant in Rio after she met the IAAF's "exceptional eligibility criteria."