Manchester City will conduct an internal investigation after being left "disappointed" by Benjamin Mendy's breach of COVID-19 protocols.
France international Mendy - who has made nine appearances in all competitions this season - is reported to have staged a party on New Year's Eve that included guests from outside his household.
In a statement, the Premier League club confirmed they are aware of the situation involving the player, who has since apologised for his error amid the ongoing coronavirus pandemic.
City are without a number of first-team players following an outbreak of the virus that forced their game away at Everton on December 28 to be postponed.
"The club is aware of a New Year's Eve Covid-19 breach involving Benjamin Mendy and the subsequent media reporting of it," City said in a widely reported statement.
"While it is understood that elements of this incident have been misinterpreted in the reports, and that the player has publicly apologised for his error, the club is disappointed to learn of the transgression and will be conducting an internal investigation."
Pep Guardiola confirmed on Friday that three more "important" members of the first team had tested positive, following on from confirmed cases for Gabriel Jesus and Kyle Walker, as well as two members of staff.
City closed the training facility due to the situation within the club, though the squad were able to return to work on Wednesday ahead of Sunday's trip to Chelsea.
They are not the only top-flight team to be dealing with a coronavirus outbreak, though. Fulham have had festive fixtures against Tottenham and Burnley cancelled.