The Court of Arbitration for Sport (CAS) has allowed Russia's lone track and field athlete, long jumper Darya Klishina, to compete at the Rio Games.
In a statement, the court said it granted Klishina's appeal because she fulfilled the requirements laid out by the ruling athletics body IAAF and indicated that she could compete in qualifying on Tuesday.
US-based Klishina was the only Russian athlete allowed in at the Rio Games by the IAAF because she underwent doping tests outside Russia. The IAAF then suspended her on Saturday based on new information from a report by Canadian lawyer Richard McLaren.
But the CAS said "the previous decision of the IAAF, that the athlete complied with the relevant criteria because of her permanent residence outside Russia, still applied despite the additional information provided by Prof. McLaren."
The IAAF on Monday confirmed the CAS decision to allow Klishina to compete in a brief four-line statement.
"We instigated a review process following new evidence presented to us. The outcome we reached to revoke Darya Klishina's exceptional eligibility was not upheld by CAS despite the information received from McLaren and she is therefore eligible to compete in Rio," read the statement.
A July 24 report for the World Anti-Doping Agency (WADA) revealed widespread and state-sponsored doping in Russia.
Russia escaped a blanket ban despite the grave allegations, but its athletes had to meet strict criteria to compete in Brazil, with some 280 of them now at the Games.
United States-based Klishina had been the only Russian track and field athlete allowed to compete in Rio, after the Russian athletics federation was suspended over doping practices in the country and its other 67 proposed Olympic athletes were banned - a ruling that was confirmed by CAS last month.
Klishina, the two-time European indoor champion, came in for criticism at home and was accused of being a traitor on some Russian social media sites.
Russian officials celebrated the CAS ruling as an important victory.
"Justice triumphed," Dmitry Svishchev, chairman of the State Duma Committee on Culture, Sports and Youth Affairs, told the Tass agency.
"The court understood that there were no facts about any kind of violation."
"Now we need to settle down and wish Dasha (Klishina) good luck," sports minister Vitaly Mutko said on Interfax agency.
The former president of Russia's athletics federation Valentin Balakhnichev said he was happy about the CAS ruling, which he also did not expect. The whole incident looks like there were political motives behind it.