Lars-Jorgen Salvesen had a night to remember as Derby beat Hull 2-1 at Pride Park.
The Norwegian striker took advantage of a mistake by goalkeeper Ivor Pandur to score his first goal for the club and give Derby a fourth straight victory.
Carlton Morris had followed his hat-trick against Sheffield United on Saturday with a first-half header to put Derby in front but Hull hit back in the second half.
Joel Ndala scored his first senior league goal but Hull's six-game unbeaten run was ended by Pandur's late error.
The game began in pouring rain and the slippery conditions resulted in a mistake by Derby's Bobby Clark in the 13th minute which allowed Matt Crooks to fire in a 20-yard shot which came off the top of the bar.
Derby had the best chance in the 26th minute when Ben Brereton Diaz played in Patrick Agyemang whose shot was deflected behind but after Hull conceded another corner, Morris struck.
Joe Ward swung the ball in and the Derby captain rose highest to head firmly into the bottom right corner of Pandur's net.
Since Crooks rattled the woodwork, Hull had created little and they went in at half-time with a lot to do to unsettle Derby's well-drilled defence.
Whatever was said had an impact because The Tigers bared their teeth and after Crooks had a shot saved, they drew level in the 50th minute.
Joe Gelhardt played the ball to the back post and after Ward and Jacob Widell Zetterstrom collided, Ndala slammed the ball into the roof of the net.
Hull were transformed as an attacking force and it needed a great sliding tackle to block a Regan Slater shot.
The visitors continued to mount some dangerous attacks but Derby's defence was standing firm and they took advantage of a dreadful mistake by Pandur to retake the lead in the 83rd minute.
The keeper was slow in making what should have been a routine clearance and when Andi Weimann closed him down, the ball broke to Salvesen who fired into an empty net from outside the area.
Pandur lay face down on the wet turf aware that he had almost certainly cost his side the game, although six minutes of added time gave the visitors hope of salvaging a draw.
They whipped in several dangerous balls but Derby defended well and Salvesen almost had a second on the break before the final whistle confirmed another big result for John Eustace's improving team.
The managers
Derby's John Eustace:
To follow...
Hull's Sergej Jakirovic:
To follow...