West Ham have confirmed manager David Moyes, plus players Issa Diop and Josh Cullen have tested positive for Covid-19.
The Hammers are playing Hull in a third-round Carabao Cup tie, which Diop and Cullen were due to start.
They were replaced and Moyes was not on the touchline, instead assistant manager Alan Irvine taking charge of the tie.
West Ham have since confirmed the trio have returned a positive Covid-19 test and immediately left the stadium.
They said in a statement: " West Ham United can confirm that David Moyes, Issa Diop and Josh Cullen have returned positive tests for COVID-19.
"The Club’s medical team were informed of the test results as the team were at London Stadium preparing for this evening’s Carabao Cup third round tie against Hull City.
"The manager and both players immediately left the stadium and have returned home. All three, who are asymptomatic, will now follow Public Health England and Premier League guidelines and protocols.
"Everyone at West Ham United send their best wishes to David, Issa and Josh. Tuesday’s match will go ahead as planned, with Assistant Manager Alan Irvine taking charge of the team."
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Moyes previously self-isolated at the start of the pandemic after Arsenal boss Mikel Arteta tested positive.
The Scot went into isolation as a precautionary measure after coming into contact with Artet following a fixture between the Hammers and the Gunners.
Arteta's positive test directly led to the suspension of the 2019-20 season.