Derby’s hopes of ending a traumatic season on a high were crushed by Jordan Hugill’s second-half goal which gave Cardiff a 1-0 win.
With Derby already relegated to Sky Bet League One following a points deduction for entering administration, they wanted to give a 29,000-plus crowd a victory to cheer but Hugill’s close-range finish denied them.
Derby dominated for long periods with Cardiff goalkeeper Dillon Phillips making crucial saves from Liam Thompson, Tom Lawrence and Louie Sibley before Hugill pounced.
With a takeover of the club by American businessman Chris Kirchner moving closer, there was an air of optimism around Pride Park and Derby responded with a strong start that pushed Cardiff back.
The promising young winger Malcolm Ebiowei curled a shot over after Lawrence fired a free-kick into the wall of blue shirts.
Derby were dominating possession but, after 25 minutes, had not forced Phillips into action while Cardiff had barely figured as an attacking force.
Phillips had to dive at his near post to hold a deflected header from Craig Forsyth in the 28th minute and the Cardiff keeper had to make a far better save eight minutes later when he dived to his left to turn away a Liam Thompson shot from just outside the area.
Phillips kept his side on level terms with two saves in the space of a minute as Derby pressed for the goal their control merited. A Lawrence shot from 20 yards was heading for the top left corner until Phillips clawed it away and he denied Sibley at the back post after a corner was flicked on.
Cardiff finished the half with a rare attack which ended with Hugill appealing for a penalty when he tangled with Jason Knight but referee Keith Stroud was not interested.
It had been a distinctly end-of-season display from Cardiff but they emerged with more purpose for the second half and went ahead in the 55th minute.
Eli King showed good close control inside the area before cutting the ball back for Hugill to turn past Ryan Allsop from six yards.
Derby responded with a move down the right that set up Forsyth for a shot from just inside the area that Phillips held.
Cardiff were looking to hit Derby on the break but they came close to conceding in the 83rd minute when a poor clearance fell to Ravel Morrison on the edge of the box and his shot beat Phillips but went just over.
In a frantic finish, Derby had claims for a penalty turned down before Curtis Davies was denied by Phillips in the final minute of added time.
