Derby interim manager Wayne Rooney and the club's entire first-team squad will miss Saturday's FA Cup third-round trip to Chorley due to a coronavirus outbreak resulting in nine positive tests among players and staff.
The Rams will instead send a group of players from the club's under-23 and under-18s teams as they operate within a different bubble and will also be tested on Thursday morning.
"The first team and coaching staff are in isolation until early next week when they are re-tested," Derby chief executive Stephen Pearce told Sky Sports.
"But we will be able to fulfil our fixture against Chorley as the Football Association regulations are slightly different to the EFL (English Football League).
"If you've got 14 registered players -- and it doesn't matter whether they are academy registered or first-team registered -- you are obliged to fulfil the fixture if you can, unless for other reasons if you want to apply.
"We still have 16 players we are still able to put out on Saturday. As a club we're quite pleased to do that and we're keen to get the game up and running."
Derby have closed their training ground due to the outbreak with the youngsters set to prepare for the tie at nearby St George's Park, the FA's national football centre.
The news comes as a blow to non-league Chorley, who had been preparing to welcome former England captain Rooney.
"The last thing we want is to be playing against an under-18 side. It's our chance to shine against good players," said Chorley manager Jamie Vermiglio.
"For Wayne Rooney to come would just be the pinnacle for us."