Johnny Russell made the perfect entrance to give Steve McClaren a winning start as his side beat Leeds 1-0 at the iPro Stadium.
Russell smashed a low shot in from the edge of the area four minutes after coming on as a second half sub to earn Derby's first home championship victory of the season.
Leeds almost spoiled McClaren's return when sub Marcus Antonsson hit a post in stoppage time but Derby held on in front of a 31,000-plus crowd.
It was no surprise that McClaren switched to his favoured 4-3-3 formation but a long-range effort from Bradley Johnson that cleared the bar was as close as Derby came in a tepid opening 20 minutes.
Hadi Sacko almost went clear for Leeds before Jacob Butterfield fired over from 25 yards in the 26th minute but the visitors fashioned an opening a minute later when Luke Ayling crossed from the right and Chris Wood flashed a header wide.
Derby responded with a clever chip from Johnson that put Matej Vydra behind Leeds on the left but the striker's low shot fizzed just past Rob Green's far post.
Butterfield was off target with another effort from distance and Sacko was close to getting on the end of a Pablo Hernandez pass in the 42nd minute before a disappointing half ended with Kyle Bartley thumping a header against the bar from a Alex Mowatt corner.
Derby were forced into a change in the 52nd minute when Ikechi Anya limped off following a robust challenge from Bartley and his replacement Russell fired the home side ahead four minutes later.
A corner was only cleared as far as the edge of the box and Russell was the first to the loose ball and drove a low shot past Green for his first goal of the season.
Green was probably unsighted as the ball skidded past him but he kept Leeds in it in the 64th minute when he plunged to his left to beat away a 20 yard shot from Will Hughes.
Derby thought they had scored a second in the 68th minute when Tom Ince broke away down the right and his low cross was turned in by Vydra but the Czech striker had just strayed offside.
Scott Carson had not made a meaningful save in the game but he kept Derby in front when he got down quickly to his left to stop a Kalvin Phillips 25-yard free-kick squeezing inside the post.
Leeds pressed hard for an equaliser and almost got it in the fifth minute of added time when Antonsson curled a right foot shot past Carson but the ball came back off a post.