Four Barcelona players were subjected to a surprise test on Thusday morning. Representatives from the Spanish health protection service in sport turned up at the training ground.
They set to work on Jordi Alba, Marc-Andre ter Stegen, central midfielder Denis Suarez and striker Luis Suarez.
They took doping control tests, of the type also taken on occasion by UEFA.
The four players were then able to join the training session with their team-mates, as Barcelona prepare for their final game of the league season against Eibar on Sunday at Camp Nou.