The 12th-placed Tigers have also played a game more than the teams from fourth to seventh, including Derby, who are kept out of the top six on goal difference.
Hull manager Nigel Adkins was left to reflect on Kamil Grosicki’s early miss and what he admitted was a “shocking” goal to concede.
“We did really well to create a situation with a great square pass from Fraizer Campbell to put Kamil free for basically an open goal and he hits the post, so that could have changed the complexion of the game, “said Adkins.
“We had a few ifs, buts and maybe, but for me we’ve conceded a shocking goal, there’s a tackle to be made in the middle of the pitch and we haven’t made it, which is really poor,
“We knew the wide players would be coming in off the line and the full-backs are highlighted to make sure we get good defensive blocks in, but we haven’t done it.
“That was really disappointing and then we were just about to make a change in the second half and again poor defending allowed them to create an opportunity to go and score.”
Opposite number Frank Lampard hailed Martyn Waghorn’s quality after the striker joined the 100 club.
Waghorn responded to Lampard’s decision to play him as the main striker by netting his 100th career goal near the end of a tight first half.
Hull should have been ahead when Grosicki had the goal at his mercy from 12 yards, but hit the outside of a post and the visitors were made to regret that when Waghorn pounced in the 41st minute.
A clever pass from Duane Holmes sent him in behind Hull’s backline and, although David Marshall saved, Waghorn drove in the rebound.
Fikayo Tomori headed a corner wide before Hull went close on the hour when Grosicki’s cross was glanced inches wide by Jackson Irvine.
Waghorn made sure of the double over Hull to go with Derby’s Carabao Cup win at the KC Stadium when he dispatched Jayden Bogle’s low cross in the 71st minute.
“The best thing about the game was we were clinical in our finishing with two great finishes from Martyn Waghorn and in the end it was pretty comfortable against a good team,” said Lampard. “It was an all-round performance of work-rate, quality, hold-up play and two great goals.”
Derby County: Roos, Bogle, Keogh, Tomori, Malone, Bryson, Huddlestone, Holmes (King 81), Harry Wilson, Waghorn (Cole 90), Jozefzoon (Bennett 59). Unused substitutes: Wisdom, Johnson, Nugent, Ravas.
Hull City: Marshall, Kane, McKenzie, Lichaj, Kingsley (Ridgewell 75), Bowen (Pugh 75), Henriksen, Stewart (Evandro 72), Grosicki, Irvine, Campbell. Unused substitutes: Dicko, Milinkovic, Long, Batty.
Referee: G Ward (Surrey).