Wayne Rooney and Derby's entire first-team squad will miss Saturday's FA Cup tie against Chorley following the coronavirus outbreak which has closed their training ground, the PA news agency understands.
The Rams will instead field a team made up of under-23 and under-18 players at Victory Park on Saturday afternoon.
A number of first-team players and staff returned positive tests for Covid-19 on Monday, with the club's Moor Farm facilities subsequently closed.
In a statement issued following those tests, Derby had said they were "in dialogue with the EFL and Football Association in relation to upcoming fixtures".
FA Cup rules state that clubs are expected to fulfil their fixtures if they have 14 eligible players – including from the under-23 and under-18 squads – available, though there is scope for appeal.
The fixture at Chorley's Victory Park has been selected for live TV coverage and is scheduled to kick-off at 12.15pm on Saturday.
In addition to the first-team players out, Derby's options could be further depleted, with several members of the under-23 squad having trained with the first team in recent days.
Jahmal Hector-Ingram, Louie Watson, Morgan Whittaker and Kaide Gordon were all in the squad for Friday's 1-0 defeat away to Sheffield Wednesday.
Though the news may improve Chorley's chances of continuing a cup run which has already delivered victories over Peterborough and Wigan, it will come as a disappointment for the National League North side, who are already having to play one of their biggest ever fixtures behind closed doors.
Speaking before the news was confirmed, manager Jamie Vermiglio said Rooney's presence at Victory Park would be huge for Chorley.
"I just hope he's here," Vermiglio said. "There's a big build-up with it being Wayne Rooney's side and he's an absolute legend with Manchester United and what he's done as a footballer.
"From a personal point of view, and the players and the fans, we want to see Wayne Rooney walk into Victory Park.
"We want to be able to shake his hand, or fist pump or elbow bump.
"Even though it would disadvantage us if he were here, it would give the occasion a little bit more merit.
"The last thing we want is to be playing against an under-18 side. It's our chance to shine against good players.
"For Wayne Rooney to come would just be the pinnacle for us."
