Aberdeen FC say a first-team player has tested positive for Covid-19.
It follows mandatory twice-weekly testing being undertaken after a return to training.
In a statement the Dons said: "No other members of the first team, coaching staff or essential staff at the training ground tested positive.
"The individual, who is asymptomatic, has been self-isolating since receiving the test result and will be in regular contact with the medical staff at Cormack Park before he returns to training.
"Since training resumed, the club has strictly followed the Joint Response Group protocols including social distancing, increased sanitisation practices, twice weekly testing, and small group training sessions. It’s therefore unlikely there will be any risk to the wider player group and the planned training schedule will not be impacted.
"The club is satisfied that the regular testing regime, provided by The Aberdeen Clinic, together with the stringent hygiene and safety measures in place are working effectively."