Non-league Chorley beat coronavirus-affected Derby 2-0 to knock the Sky Bet Championship club out of the FA Cup at the third-round stage.
Yet with the Championship visitors decimated by a Covid-19 outbreak at their club, the four division gap between the sides was wiped out, handing the initiative to the part-timers.
Derby, with interim manager Wayne Rooney and their entire first-team squad isolating, were forced to field a team made up from their youth sides in order to fulfil the fixture.
With an average age of just 19 and not a single game of first-team experience amongst them, it was an uphill struggle.
There was an early flashpoint when Derby’s Cameron Creswell went down in the Chorley area attempting to go round former Bradford goalkeeper Matt Urwin after being played through by Isaac Hutchinson. The Rams felt they should have had a penalty but referee Kevin Friend ruled in Chorley’s favour.
That was a rare moment of alarm for the home team, who soon established themselves as the stronger side.
Their opener came from a corner taken by Willem Tomlinson, with his deep cross leading to a series of headers in the Derby box. The visitors struggled to clear and former Bolton striker Hall got the final touch from close range.
Hall had another chance early in the second half but headed narrowly wide and Arlen Birch then delivered an inviting cross into the Derby box but Calveley planted a header wide.
Calveley was not to rue the miss for long. Derby barely got a foothold in the game and former Port Vale midfielder Calveley made victory certain six minutes from time when he volleyed in from close range.
