Sam Winnall scored two second-half goals as in-form Derby inflicted more misery on Leeds with a 2-1 victory at Elland Road.
The on-loan Sheffield Wednesday striker took his goal tally to three in his last two games to ensure Gary Rowett's side came from behind to claim a fourth consecutive victory, extending their unbeaten run to seven matches.
Winnall repaid Rowett's faith for handing him a start by netting the equaliser from close range before converting from the penalty spot, although replays suggested Tom Lawrence was bundled over outside the box.
Pierre-Michel Lasogga fired Leeds into a deserved lead but a sixth defeat in their last seven games in all competitions, including three in a row at home, has heaped the pressure on boss Thomas Christiansen following the club's fine start to the season.
Leeds went ahead in the eighth minute when Ronaldo Vieira won the ball in midfield, fed Samuel Saiz and the playmaker found Lasogga who fired his fifth goal of the campaign low into the bottom corner.
The hosts broke at pace again soon after the goal but Derby managed to scramble clear after Vieira's pass was too heavy for Ezgjan Alioski.
Alioski was in the action again five minutes before half-time, going to ground at the back post under the challenge of Andre Wisdom attempting to get on the end of Kemar Roofe's cross, yet referee Simon Hooper waved away strong penalty appeals.
Leeds continued where they left off in the first half at the start of the second, on the front foot, and Roofe curled a shot over the top. Alioski almost caught Scott Carson out with a sliced cross that the goalkeeper just tipped wide before Saiz broke and fired a 25-yard shot over the top.
Derby showed signs of waking up on the hour mark as a diving Chris Martin failed to connect with a Bradley Johnson cross before the striker's low effort was saved by Andy Lonergan.
And County drew level after 72 minutes when Winnall tapped in Craig Forsyth's cross from close range after the left-back broke clear.
Winnall netted the winner just eight minutes later from the penalty spot after referee Hooper adjudged that substitute Hadi Sacko had pulled Lawrence to the ground in the box rather than outside.
Winnall sent Lonergan the wrong way and, as Leeds pressed for an equaliser, the visitors continued to look dangerous. But Leeds had a chance to equalise as the game headed into stoppage time, Lasogga firing over from just outside the box.
The managers
Thomas Christiansen: "In the mood that I am right now, it is better not to speak. I believe all of you have seen the different situations in the game. There was a clear penalty in the 44th minute against Alioski. And the non-penalty that was given in the second half. Against that, I feel impotent.
"It is a shame for the players that they should suffer a defeat because of only one person took those decisions. It is difficult for me to control the situation when it is not in my hands. We didn't deserve it. The defeat is very bad, another defeat, and we have to change. We need the win on Saturday against Brentford. It cannot go on like that. But I am satisfied with the team. We need to continue and give it even more. On Saturday it is another final."
Gary Rowett: "At the time, I couldn't really see [the penalty incident] because it was right in the far corner. I have watched it around five times and I still cannot work it out. It's not obviously inside and it's not obviously outside either, and it is very close. I can understand why Leeds a little bit disappointed by that.
"[Winnall] has reacted brilliantly. He got his deserved start and scored two excellent goals. He has got that real killer instinct in the box There was nobody other than him taking the penalty."