Liverpool defender Mamadou Sakho is being investigated by UEFA for an alleged anti-doping allegation.
The 26-year-old France international has been omitted from the Liverpool team to face Newcastle United in Saturday's Premier League game as a result, but he has not been suspended from playing.
A statement on Liverpool's official website read: "Yesterday, Friday 22nd April 2016, a formal communication was received from UEFA stating that they are investigating a possible anti-doping rule violation by Mamadou Sakho.
"The player will respond to UEFA on the matter.
"The player is currently not subject to any playing suspension. However, the club, in consultation with the player, has decided that while this process is followed the player will not be available for selection for matches.
"There will be no further comment at this time."