Matej Vydra and Bradley Johnson each bagged a brace as Derby dismantled Hull, whose wretched form on the road continued to haunt them in a humiliating 5-0 defeat at Pride Park Stadium.
Vydra scored either side of Sebastian Larsson skying a spot kick that would have brought Hull level and City trailed 4-0 at half-time after Curtis Davies and Johnson got on the scoresheet.
Johnson was also on-target just before the hour mark to leave the visitors counting the cost of a third successive away defeat in all competitions.
Hull have not won on their travels since October last year and have suffered 19 losses in 22 games during that period.
Their shortcomings were ruthlessly exposed by a Derby side who bounced back from a 3-1 defeat to Sheffield United before the international break to record their biggest win since November 2014.
The Rams made two changes following the collapse of Maikel Kieftenbeld's move from Birmingham while Hull made four with three new signings making their debuts.
Tom Huddlestone and Davies were facing their former club, who fell behind to Vydra's superb free kick after 15 minutes.
Vydra was tripped a couple of yards outside the area and he sent the ball around the left edge of the defensive wall and past Allan McGregor's despairing dive.
Hull were given a great chance to equalise in the 27th minute when Ola Aina was pulled down by Tom Lawrence at the back post but Larsson made a complete hash of the penalty, spooning his kick high over the bar after a stuttering run-up.
It proved a costly miss because Derby extended their lead in the 34th minute when David Nugent ran through the middle of the defence too easily and laid the ball back to Vydra, who smashed the ball in from 12 yards.
The night got even worse for Hull four minutes later when they conceded a corner which Lawrence swung over and Davies got in front of a defender to head inside the right post for a goal on his 400th league appearance.
McGregor denied Vydra but from the corner, Hull failed to clear and Lawrence whipped the ball back in for Johnson to tap in unmarked at the back post to complete a great first half for Derby but a desperate one for the visitors.
It was now a case of damage limitation for Hull but after Jarrod Bowen just failed to connect with a diving header, they handed Derby a fifth in the 58th minute.
Michael Hector tried to be too clever with a clearance from the goal-line and only got it as far as Johnson just outside the box. He took a touch before firing past McGregor.
Aina did force Scott Carson into a save when he tipped over the right-back's header in the 69th minute but by then many of the visiting fans had left Pride Park trying to come to terms with what they had witnessed.