Chris Wood headed the winner as Leeds beat Derby 1-0 at Elland Road to go third in the Sky Bet Championship.
The striker nodded home on the stroke of half-time for the home side on Friday night to claim a third-straight win in all competitions for Garry Monk's side.
Derby's miserable night was compounded late on as Bradley Johnson was dismissed to leave them with 10 men at full-time.
The Rams had the chance to climb into the play-off places, but instead remain seventh ahead of the rest of the weekend's action.
Leeds dominated virtually from the start at as Derby struggled to cope with their pace, power and movement up front.
Pablo Hernandez, in particular, was causing real problems for the home side, but it was Kyle Bartley whom all the best chances fell to initially.
The defender had three golden opportunities in as many minutes midway through the first half, denied by goalkeeper Scott Carson on the first two occasions before somehow managing to poke the ball wide from two yards with the third.
That didn't stop Leeds pushing forward, though, and they finally got their deserved breakthrough after 45 minutes as striker Wood rose highest from a corner and nodded home from six yards.
Derby's forays forward were few and far between in the first half, with Tom Ince their own real threat. And it was he who forced the first real save from Rob Green moments after they fell behind, as his powerful shot stung the palms of the Leeds goalkeeper.
McClaren made a double Derby change at the break as Will Hughes and Matej Vydra replaced Julien De Sart and Abdoul Camara.
And it paid immediate dividends as their display improved immediately. They even had the ball in the back of the net after 50 minutes, when Rob Green's attempted clearance hit Darren Bent before flying into the net. But the ball struck the arms of the striker and it was rightly ruled out.
The renaissance was short-lived, though, and Leeds were soon back on top, although chances were hard to come by throughout most of the second half.
McClaren tried to change things up again by throwing on David Nugent for his debut, but the striker who has been very short on football this season at Middlesbrough struggled to make any real impression.
It then went from bad to worse for Derby as Johnson saw red for a second bookable offence, having clumsily challenged Stuart Dallas in the 89th minute.
Leeds boss Garry Monk:
"I'm extremely proud of my boys. I said to them before the game to show the values we hold to ourselves and how we are as a group. I wanted them to show that on the pitch and we got that.
"The first half was breathtaking at times. We choked them by the throat and should have scored a few more goals. As a performance it was exactly what we were looking for.
"We're moving in the right way, enjoying our football and working hard."
Derby boss Steve McClaren:
"It's not like us whatosever. I thought Leeds were excellent. We went to West Brom with the same team last week but we didn't follow that on. We have to do it every week and if you're a little bit short against good teams you get beat.
"We talked about the midfield being vital, we had to win that and it was a big area where we lost out. They dominated us in that area. We didn't deserve anything from the game but that's the Championship, we dust ourselves down and go again on Monday."