An anti-doping case has been opened against Russian medal-winning curler Alexander Krushelnitsky, says the Court of Arbitration for Sport (Cas).
Krushelnitsky, who won Winter Olympic bronze with wife Anastasia Bryzgalova in the mixed doubles, is suspected of testing positive for meldonium.
Cas opened a case against the 25-year-old following a request from the International Olympic Committee (IOC).
A hearing date has not been set and a B sample result is expected on Monday.
More than 160 competitors are in the Olympic athletes from Russia (OAR) team as their country was banned from the Games over “systemic” doping at Sochi 2014, which they hosted.
Russian athletes who could prove they are clean could compete under the OAR banner, with the team comprising 168 competitors – the third biggest behind Canada and the United States.
“It’s a huge embarrassment for the IOC, given it let OAR compete,” said BBC commentator Steve Cram.
The Reuters news agency originally confirmed the identity of the athlete with a Russian Olympic delegation spokesman.
A spokesman for the IOC said it would be “extremely disappointing for us if a case is proven”.
An IOC statement added: “Doping, testing and sanctioning at the Olympic Winter Games Pyeongchang 2018 is independent from the IOC. Therefore the IOC cannot communicate on individual cases while the procedure is ongoing.”