The side was set to train for the upcoming season when the COVID-19 outbreak was verified with no other player or staff testing positive at this time.
The unidentified player has mild symptoms of the virus and is quarantined at his residence while the rest of the team trained as scheduled yesterday evening.
All PAOK players and staff will be tested again today for the virus.
Meanwhile, the Greek water polo federation announced on Sunday that four more players of the men's national team have tested positive to COVID-19 and have been placed in quarantine.
On Saturday it was announced by the federation that one player had tested positive to the virus, bringing to five totally.