Manchester City striker Gabriel Jesus and defender Kyle Walker have tested positive for Covid-19, the Premier League club revealed on Friday.
Two other City staff members have also tested positive for the coronavirus, and all four are self-isolating.
Both players featured in City's 4-1 League Cup win over Arsenal on Tuesday, with City due to host Newcastle in the Premier League on Boxing Day.
A club statement said: "Manchester City FC can confirm that Gabriel Jesus, Kyle Walker, and two members of staff have tested positive for COVID-19.
"All four personnel will now observe a period of self-isolation in accordance with Premier League and UK Government protocol on quarantine.
"Everyone at the club wishes our colleagues a speedy recovery over the Christmas period ahead of their return to work, training and competition."
City, eighth in the league table, visiting Everton on Monday after the Newcastle game.