The spying row dominated the build-up before the game with United head coach Marcelo Bielsa admitting he sent a scout to watch Derby in training. But it only served to fire up home fans at Elland Road and they were rewarded with a 2-0 win courtesy of a first half goal from Kemar Roofe and a second half effort by Jack Harrison.
The Whites were bristling from the start and swarmed all over their promotion rivals to open up a five-point gap at the top of the Sky Bet Championship.
They were robbed of a first minute goal by poor officiating as Ezgjan Alioski was played in and brought down inside the box by Andre Wisdom. Referee Andy Davies pointed to the penalty spot, but changed his mind when seeing that the linesman was flagging for offside.
Replays showed that Alioski was clearly onside, but Derby escaped and they survived again soon after when a Pablo Hernandez corner was headed on by Pontus Jansson and turned over from close range by returning skipper Liam Cooper after the ball was just behind him.
With the fans in full voice Derby were rattled and Kemar Roofe raced onto a pass just inside the box only to scuff his shot with visiting keeper Scott Carson able to save comfortably.
Wisdom, who would surely have been booked on the penalty incident, was lucky to stay on the pitch as he scythed down Alioski and Leeds players were simply quicker to every ball at this stage.
The opening goal came on 20 minutes when brilliant wingplay by 18-year-old Jack Clarke saw him cross low where Roofe was in like a flash to crash the ball into the top corner of the net.
Soon after Clarke latched onto Hernandez’s great pass and juggled with the ball one way then the other before sending his volley wide from the edge of the box.
Adam Forshaw was much improved in a dominating midfield display and his cross was met by Jack Harrison, but his header lacked power and was comfortably saved by Carson.
Tom Lawrence managed Derby’s first effort on goal after 33 minutes only to fire his 25-yard shot well over.
At the other end Luke Ayling could not quite flick the ball goalwards from an angled free-kick played into the area.
Forshaw then went close with a swerving strike from distance that was unlucky not to bend just inside the far post.
The visitors finally fashioned a bit of a chance, but Mason Mount’s shot was well blocked by Ayling.
United made another lightning start to the second half as they increased their lead within two minutes. Clarke’s mis-hit cross could only be tipped away by Carson and Alioski was forward from his left-back position to slide the ball across for Harrison to score with a tap-in.
Leeds had an escape two minutes later when keeper Bailey Peacock-Farrell charged way out of his goal and was fortunate to block David Nugent’s attempt to shoot from long range.
Peacock-Farrell then made his only other save as he comfortably caught the ball from Duane Holmes’ header.
The hosts were soon back on top, however, as Jansson’s stooping header sent the ball over and substitute Jamie Shackleton’s cross shot went close after Clarke played him in down the side.
Roofe was inches away from connecting with a Clarke low cross after the young winger had again made a fine run down the flank.
Lawrence sent a 25-yard shot well wide to plenty of heckles from the home fans before Hernandez tried a volley from a difficult angle only to hit the side netting.
Derby threw on substitutes, went two up top and Leeds went to a back three system, but the closing stages were seen out without much alarm as Leeds completed possibly their most satisfying victory of the season so far. After three straight defeats - two in the league - the pressure was on and the players responded magnificently.
Head coach Marcelo Bielsa thanked home fans for their backing in the big game.
He said: “It was a very complete game and the fans have never supported us as much as tonight.
“The fans understood that it was a very important game so they gave us all their support.
“The fans and the team understood the importance of this game and they united. The team played in a way which deserved the support.”
“The win was very important.”
Leeds United 2
(Roofe 20, Harrison 47)
Derby County 0
Friday, January 11, 2018
Sky Bet Championship
Leeds: Peacock-Farrell, Ayling, Jansson, Cooper, Alioski, Forshaw, Clarke (Davis 79), Klich, Hernandez, Harrison (Shackleton 63), Roofe.
Derby: Carson, Wisdom (Nugent 45), Keogh, Tomori, Lowe, Evans (Jozefzoon 61), Bryson, Holmes, Mount, Lawrence, Marriott (Waghorn 72).
Referee: Andy Davies