The Football Association (FA) will investigate allegations of spying after Derby County claimed a man caught by police acting "suspiciously" near their training ground was a Leeds United employee.
The day before the two teams' Championship encounter at Elland Road on Friday, police were called to Derby's training centre after growing concerned with the behaviour of a man outside the premises.
Police confirmed a man was found and questioned at the perimeter fence of the complex, before being sent on his way with no arrest made.
Media reports claimed the man involved was a "spy" sent by Leeds, also alleging he had damaged a fence, though police insisted the latter was untrue.
While authorities made no explicit connection between the man and Leeds, Derby insist it was made known to them that he was an employee on the football staff at Elland Road.
"Derby County Football Club can confirm that officers from the Derbyshire Constabulary were called to the Derby County Training Centre at around 11:20am on Thursday 10th January 2019 following reports of a man acting suspiciously outside the premises," Derby said in a statement.
"It has since been confirmed to Derby County that the individual concerned is an employee of the footballing staff at Leeds United Football Club.
"The club is now in discussion with Leeds United club officials in relation to this incident."
The FA is now also preparing to look into the matter.
In a statement released to Omnisport, an FA spokesperson said: "We are aware of the incident at Derby County's training ground and we will be investigating the matter."