West Ham United boss David Moyes and two of the Hammers playing staff have returned positive tests for coronavirus, the club confirmed on Tuesday.
The trio were forced to leave London Stadium, with Diop and Cullen replaced in the Hammers first team by Harrison Ashby and Jack Wilshere.
The east London club subsequently revealed that positive tests for Covid-19 was behind their withdrawals, while confirming that the game would go ahead as planned.
"West Ham United can confirm that David Moyes, Issa Diop and Josh Cullen have returned positive tests for Covid-19," the club explained in a statement published on its official website on Tuesday.
"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 sends 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.
"The club’s measures and protocols around Covid-19 remain stringent. This included offering to test the Hull City team ahead of tonight’s fixture – an offer which they opted not to accept."
There have been some late changes to our line-up tonight.— West Ham United (@WestHam) September 22, 2020
Issa Diop and Josh Cullen will be replaced by Harrison Ashby and Jack Wilshere in the Starting XI. David Martin is also now named among our substitutes.https://t.co/DAuCGvyES3
West Ham United can confirm that David Moyes, Issa Diop and Josh Cullen have returned positive tests for COVID-19.— West Ham United (@WestHam) September 22, 2020
The match against Hull went ahead as planned, with West Ham easing to a 5-1 victory over the League One side thanks to a first half-strike by Robert Snodgrass and a pair of braces by Andrey Yarmolenko and Sebastian Haller.
It comes after another Carabao Cup match, between Leyton Orient and Tottenham Hotspur, was postponed because of an outbreak of coronavirus among the League Two side's squad.
The EFL did not announce a decision on the outcome of the match, with speculation growing that Tottenham could be awarded a win by forfeit.