Debutant Sam Baldock ended Derby's nine-game run without a Championship victory by securing a 1-0 triumph at Hull.
The 32-year-old forward, who did not manage to find the net in any of his 23 outings for Reading last season, settled the contest with a predatory 57th-minute finish.
Baldock was one of two new signings who were thrown straight into the team at the MKM Stadium by Rams boss Wayne Rooney, with 39-year-old veteran Phil Jagielka marshalling the visitors' defence to a clean sheet at the other end.
For Hull, the defeat represented a fifth loss in their last six meetings with Derby.
The visitors had made all of the early running with Kamil Jozwiak receiving the ball from Lee Buchanan before galloping across the edge of the penalty box and dragging wide.
Next, Louie Sibley burst into the penalty area to latch on to Baldock's lay-off but his shot lacked the power to trouble home keeper Matt Ingram.
Ravel Morrison then lifted a 20-yard effort over after exchanging passes with Jozwiak, who went on to rattle Ingram's left-hand post after charging on to Max Bird's long ball through the right channel and cutting inside Lewie Coyle.
The Rams continued to press with Ingram plucking a curling Morrison attempt out of the air.
Grant McCann's men finally mustered their first shot of the night in the 26th minute, but Greg Docherty missed the target from 15 yards.
And Derby were soon back on the attack with Baldock bursting clear on goal through the left channel, only to fire straight at Ingram.
The ex-West Ham and Brighton forward made amends three minutes before the hour mark when he pounced from four yards to find the net off Ingram's left-hand upright after the Tigers keeper had spilled Buchanan's edge-of-the-box drive.
At the other end, Kelle Roos saved his first shot of the night in the 69th minute but a tame 20-yard Docherty effort was never going to unduly extend him.
Morrison wastefully found the defensive wall from a free-kick after Baldock's protests that he had been dragged down inches inside the 18-yard box as opposed to outside of it were ignored by the officials.
Home boss McCann responded by throwing on former England international Tom Huddlestone for his second debut for the Tigers, having been without a club for the entirety of last season after leaving Derby in the summer of 2020.
It appeared to inject some purpose into the hosts with Keane Lewis-Potter seeing a shot deflected wide, but further attempts at an equaliser grew more and more desperate.
Tom Eaves hoisted well over from 15 yards, fellow sub William Jarvis crashed a good opportunity straight at covering defender Craig Forsyth and Coyle was wayward with a harried effort as Rooney's men held on with few scares.
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