Rio de Janeiro: The world sports tribunal on Monday overturned a last-minute IAAF ban on long-jumper DaryaKlishina taking part in the Rio Olympics.
Klishina, 25, was the only Russian accepted for the Olympic track and field but the sport's world body suspended her on Friday after new information on her doping record emerged.
After a day of hearings, the Court of Arbitration (CAS) announced that Klishina's appeal had succeeded and she "remained eligible to compete in the Olympic Games in Rio."
The decision came just in time for Klishina, a former European indoor champion, to resume her campaign for the women's long-jump competition which starts on Tuesday.
The appeal was the latest fallout from the inquiry by Canadian lawyer Richard McLaren for the World Anti-Doping Agency (WADA) which accused Russia of mass 'state-sponsored' doping.
The CAS said it was McLaren who provided the "new factual elements" about Klishina which led the International Association of Athletics Federations (IAAF) to revoke her Rio eligibility.
The IAAF doping board rejected 67 athletes entered by Russia but accepted Klishina, who is based in Florida, because she lived abroad and had been through regular international doping checks after a cutoff period starting 1 January, 2014
The doping review board told the CAS hearing that "certain of the athlete's samples has been subject to tampering and manipulation," according to the tribunal's statement.
Media reports have said two bottles of Klishina's urine samples had been tampered with and one of the samples contained two different kinds of DNA.
The CAS panel decided however that despite McLaren's new information,Klishina "complied with the relevant criteria (to compete at Rio) because of her permanent residence outside Russia."
It added that Klishina "established that she was subject to fully compliant drug-testing in- and out-of-competition outside of Russia" from 2014 onwards.
Klishina had insisted in a statement after the ban was announced that she is "clean".
Her lawyers have argued that no evidence had been presented, only that McLaren had told the IAAF about the sample bottles which reportedly had scratch marks on them.
McLaren's report released in July said the Russian sports ministry and secret service found a way to open tamper-proof bottles to switch samples.
Russia had seized on the new ban on Klishina to reinforce its claim that it is the target of a campaign.
Russia's Sports Minister Vitaly Mutko, who is barred from Rio because of the doping controversy, called the IAAF ban "inhuman".
"It's possible that this won't be the last provocation," Mutko told Russian press agency TASS. "Some provocative moments are premeditated."
Neither Russian authorities, nor Klishina were immediately available to comment on the CAS verdict.