Chelsea's players and coaching staff were ordered into isolation as Callum Hudson-Odoi became the first Premier League player confirmed to have the new coronavirus late on Thursday.
The news casts the viability of this weekend's games further into doubt after Arsenal manager Mikel Arteta tested positive, also throwing their team into lockdown.
"Chelsea men's team player Callum Hudson-Odoi had a positive test result for coronavirus returned this evening," a club statement said.
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"Chelsea personnel who had recent close contact with the player in the men's team building will now self-isolate in line with government health guidelines.
"These will include initially the full men's team squad, coaching staff and a number of backroom staff."
Chelsea said they would discuss their upcoming games, starting with Sunday's trip to Aston Villa, with Premier League officials on Friday.
Hudson-Odoi displayed cold symptoms on Monday morning and has stayed away from the club since then. His test result was returned on Thursday night.
The club said despite testing positive, the 19-year-old was "doing well and looking forward to returning to the training ground as soon as it is possible".
