Derby are appealing to the English Football League to relax its rules to allow the Championship side to register new players for the 2021-22 season.
They are under an EFL transfer embargo for financial reasons, which include defaulting on payments to HMRC.
Manager Wayne Rooney had only nine registered senior players for Sunday’s pre-season match with Manchester United, two of whom were goalkeepers.
Rooney used five non-contract players in Sunday’s game at Pride Park.
Former England defender Phil Jagielka and ex-Manchester United midfielder Ravel Morrison both played.
But Rooney is presently unable to take advantage of an EFL rule to sign them.
Clubs are allowed to ‘staff up’ by offering players a 12-month contract or a six-month loan if they do not have 23 players of ‘professional standing’.
However, the definition of professional standing is a single first-team appearance in a competitive game outside the EFL Trophy.
Derby meet that threshold due to their FA Cup third round tie at Chorley last season, when they played a team of youngsters after a coronavirus outbreak ruled out Rooney’s entire first-team squad and many under-23 players as well.
As Derby were asked to play the game by the Football Association, they argue the unique circumstances around the fixture mean that the players involved should not be classed as being of professional standing.
BBC Sport understands that there is some sympathy within the Championship for Derby’s position, although that does not necessarily mean the Rams will be successful in altering the EFL’s stance.
Rooney has said if the position does not change he will not have a central defender for his side’s opening EFL game against Huddersfield Town on 7 August.