2nd Russian athlete fails doping test at Winter Olympics The failed test comes as the IOC considers whether to lift the doping ban.

 -- A second Russian athlete has failed a doping test at the Winter Olympics in Pyeongchang, days after a Russian curler had to hand back a bronze medal over a doping offense, reviving once again the doping scandal that has hung around Russia at the Games and hurting the country's chances of being reinstated for the closing ceremony this weekend.

The Russian Bobsled Federation in a statement confirmed that Nadezhda Sergeeva, a bobsled pilot for the Russian women’s team in Pyeongchang, had tested positive for a banned heart medication.

The federation’s president, Alexander Zubkov, told The Associated Press that Sergeeva denied taking the substance and team doctors had not prescribed it. The federation said that Sergeeva, 30, whose sled placed 12th in the women’s competition on Wednesday, had passed a doping test five days earlier.

“Federation representatives at the Olympics are starting to prepare a defense,” Zubkov told the AP, saying they did not understand how the substance had appeared in Sergeeva's test.

The federation did not specify what the medication in Sergeeva's sample was, but the AP cited Russian Olympic delegation officials that it was trimetazdine, a drug for treating angina and one that's included in the World Anti-Doping Agency’s list of banned substances. The drug has appeared in previous doping cases, the AP reported, noting that the Chinese swimmer, Sun Yang, an Olympic gold medalist, was banned for three months after testing positive for it in 2014. Yang said he had been prescribed it for a medical condition and had been unaware it was banned.

Sergeeva's failed test shed light again on the Russian doping scandal and marred an otherwise triumphant day for the country, whose skaters took gold and silver in the women's figure skating competition. Before the Games, Sergeeva had been a poster girl for the Russian team. Last year she appeared in a promotional video released by Zasport, the supplier for the Russian Olympic team's uniforms, in which she wore a sweater with the words, "I don't do doping" written on it.

But her positive doping test now cast further doubt on Russian hopes of being reinstated for the Games’ closing ceremony on Sunday.

The International Olympic Committee banned Russia from these Games as punishment for a coverup of systemic doping among its athletes, who are competing in Pyeongchang as neutrals. A small group of Russian athletes were allowed in under a special status -- Olympic Athletes from Russia -- after passing IOC vetting. Russia’s national flag and anthem have been forbidden from appearing throughout the Games.

Russian officials though had been holding out for a return to normality during the closing ceremony. The terms of the ban held out the chance for it to be lifted during the ceremony provided Russia had met its conditions during the Olympics, including ensuring anti-doping rules are observed and that banned athletes and officials were not permitted to appear at the Games.

The IOC is due to vote on Saturday whether to reinstate Russia’s national Olympic Committee, which would effectively mark an end to the punishments imposed on the country for the doping scandal.

But the implication of two Russian athletes for doping will increase the pressure on the IOC to keep the country out of the ceremony. The Russian curler, Aleksandr Krushelnitckii, was stripped of a bronze medal he won with his wife, Anastasia Bryzgalova, after he accepted a partial suspension for failing a doping test. Krushelnitckii has denied taking the drug meldonium that was found in both his test samples, but acknowledged the positive test results and withdrew his appeal from the Court of Arbitration for Sport (CAS) before it could officially ban him.

Russian sporting officials and Krushelnitckii have loudly protested his innocence, alleging he must have had his drink spiked. Russia’s curling federation has asked the country’s law enforcement to investigate whether Krushelnitckii could have been sabotaged. A source involved in the curler’s defense told the newspaper Kommersant that Krushelnitckii could be a victim of “doping terrorism.” The International Curling Federation will now investigate the case and decide what punishment to impose on Krushelnitckii.

Coaches and other athletes have pointed out that curling is a sport in which doping makes no sense. The drug, meldonium, is also grimly familiar to Russian athletes — its banning by WADA in 2016 wreaked havoc on the country’s sports, with dozens of Russian athletes, including tennis star Maria Sharapova testing positive for it. Some coaches and athletes have insisted that it would be absurd for Krushelnitckii to have used it given its notoriety.

“I don’t believe that a young man, a clever man, will use the same doping which was so big the last two years. It’s stupid. But Alexander is not stupid,” Russian women’s curling Coach Sergei Belanov told The Toronto Star. “Sorry, I don’t believe it.”

An IOC spokesman, Mark Adams, told reporters this week that the case could impact the decision to reinstate Russia, saying it would be taken into consideration. There have been other doping cases at these Olympics; Japanese speed skater Kei Saito and Slovenian hockey player Ziga Jeglic left the Games after failing tests.

Some had interpreted Krushelnitckii's acceptance of the suspension as a sign that Russia had struck a deal with Olympic organizers to muffle the scandal in return for reinstating the country for the ceremony.

Russia had appeared to be gearing up for the reinstatement, paying a $15 million fine to the IOC that was imposed for the doping scandal and which was a condition for lifting the ban. Some had also been encouraged by comments from South Korea’s president, Moon Jae-in, who thanked Russian sports officials at a reception this week, telling them the presence of Russian athletes had “made our games better.”

The Russian Bobsled Federation in a statement appeared to acknowledge that Sergeeva’s failed test could undo those hopes.

“The Federation and the athlete herself understand the measure of our responsibility and how what has happened can affect the fates of all the teams,” the federation said in a statement.

Russia's bobsled team had been heavily entangled in the doping scandal. The federation president, Zubkov, a former bobsledder himself, was given a life-time ban and stripped of two gold medals by the IOC for doping at the Sochi Winter Olympics in 2014. Zubkov, along with four other Russian bobsledders, were among the minority of Russian athletes who the CAS still found to have committed doping violations when it overturned IOC bans for 28 Russian athletes ahead of the Olympics for lack of evidence. The CAS converted Zubkov's life-time ban to a one-off ban for this Olympics, but still ruled he had made a violation.

Krushelnitckii's disqualification had already prompted some to argue that Russia’s Olympic ban should continue. This week Richard McLaren, the Canadian lawyer whose investigation for WADA laid the basis for the ban, told the British newspaper the Evening Standard he felt the IOC had made a "huge step backwards" in fighting state-organized doping.