Derby progressed to the Carling Cup quarter-finals at the expense of Leeds thanks to first-half goals from Emanuel Villa and Nathan Ellington.
Villa got the better of Lubomir Michalik and, with a curling left-foot shot, gave the home side an early lead.
Ellington doubled the advantage with a simple tap-in after great work by Kris Commons before Luciano Becchio's header from eight yards halved the deficit.
Leeds dominated after the break with Jermaine Beckford going close.
It was an audacious 35-yard effort from Leeds' substitute striker and the shot would have left the backpedalling Roy Carroll red faced had it hit the target.
The visitors twice came close to an equaliser either side of the hour mark, with Robert Snodgrass' curling free-kick clipping the outside of a post before Carroll was called into action to keep out Andy Robinson's well-struck 10-yard effort.
But Derby held on to reach the last eight of the League Cup for the first time since 1990.
The home side got off to the best possible start when Villa, hat-trick hero from the previous round against Brighton, opened the scoring in the sixth minute with a superb solo effort.
In the 11th minute, Paul Connolly deflected Becchio's goal-bound effort over the crossbar but then the home side doubled their lead in exquisite style.
Commons played a neat one-two with Przemyslaw Kazmierczak on the edge of the area, Commons then dummied to shoot before rolling the ball to Ellington for his fifth goal of the competition.
606: DEBATEBecchio converted Frazer Richardson's right-wing cross before the break but for all their second-half dominance, Leeds could not manage an equaliser.
Derby manager Paul Jewell:
"After 18 minutes it was one-way traffic and I was wondering how many goals we were going to score.
"I thought I might be able to actually sit back and enjoy a game for once. Every time we went forward we looked like we were going to score.
"But then, give Leeds credit, they absolutely dominated possession and scored a good goal and hit a post. They battered us for 70 minutes.
"I don't know whether we took a step back but the game totally transformed and sometimes as a manager you have to hold your hands up and say they played better than us."
Leeds manager Gary McAllister:
"I am lost for words really. I passed on my thoughts to the players and I think you can imagine what I was saying to them.
"I am not a massive follower of statistics but they had four attacks and scored twice.
"Our football was good but the last thing I wanted was to have to come out after the game and say we played wonderfully well but we are out, and that is the case and I am disappointed.
"It was the best they (Leeds) played this season but it is a cruel game at times and it is about winning."
Derby: Carroll, Connolly, Davis, Nyatanga, Stewart, Teale (Zadkovich 46), Green, Kazmierczak, Commons, Ellington (Sterjovski 81), Villa (Hulse 70).
Subs Not Used: Bywater, McEveley, Hanson, Pereplotkins.
Booked: Davis.
Goals: Villa 6, Ellington 18.
Leeds: Ankergren, Richardson, Telfer, Michalik, Parker (White 75), Snodgrass, Kilkenny (Howson 80), Douglas, Robinson (Beckford 64), Delph, Becchio.
Subs Not Used: Lucas, Prutton, Showunmi, Hughes.
Goals: Becchio 40.
Att: 18,540
Ref: Graham Laws (Tyne & Wear).
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