Ukraine striker Artem Besedin is facing a doping charge from UEFA, his club Dynamo Kiev have confirmed.
Besedin played throughout Dynamo's Europa League campaign as they finished third in Group B, behind Malmo and Copenhagen.
The 23-year-old also contributed as Ukraine qualified for Euro 2020, scoring his second international goal in a draw against Serbia last month.
Dynamo said in an official club statement they were informed on Thursday by UEFA of a possible violation of anti-doping rules.
"All of the nuances and circumstances are being clarified," the club's statement said.
"Therefore, and in keeping with the requirement for confidentiality, Dynamo Kyiv cannot provide the football community with more detailed information until the relevant procedures are complete."
Besedin has scored eight league goals in 13 appearances this season, with Dynamo second behind Shakhtar Donetsk in Ukraine's Premier League.