Norwich had scored only four home league goals before the visit of Hull and they demonstrated just why as they missed a succession of chances against the Tigers.
Even the normally reliable Josh Sargent’s confidence has been drained by Norwich’s collapse, and he skied a chance from just two yards out at the back post.
Hull goalkeeper Ivor Pandur then saved a downwards header from Shane Duffy before centre-half Ruairi McConville nodded wide for the home side.
The game was briefly held up when some home fans threw tennis balls on to the pitch in protest at plans to move 3,000 supporters as part of the redevelopment of Carrow Road.
Jeffrey Schlupp was dangerous on the left and he saw a right-foot shot come off the top of the crossbar before team-mate Oscar Schwartau shot wide.
But just as Derby County did two matches ago, Hull took full advantage of Norwich’s profligacy to score through Gelhardt on 49 minutes with their first attempt on goal to turn the game on its head.
Gelhardt latched on to Matt Crooks’ header and drove forward before sliding the ball home.
Norwich, devoid of confidence, tried to respond and Schwartau shot weakly at Pandur when he should have done better.
Kyle Joseph might have added a second for Hull when Duffy slipped to let him in before Gyabi sealed the win three minutes from time when he netted at the second attempt.
This was greeted by boos from the home fans, who chanted for Manning to go, in this huge test of Attanasio’s resolve.