Norwich City took another step towards the Premiership with a convincing performance that leaves Derby County in serious danger of sliding into the Second Division.
Although the match was in the balance up until half-time, the second period saw Norwich romp away after a mistake from keeper Lee Grant put the visitors in front.
Grant's 52nd minute mistake was ruthlessly punished by Craig Fleming and three goals in the final 12 minutes underlined the difference in class.
Norwich always looked in control once they got in front and midfielder Paul McVeigh was the main tormentor of Derby.
But George Burley's team had the chance to change the course of the match but poor finishing again proved costly.
Lee Holmes had a great opening from eight yards out in the 33rd minute, but Robert Green saved his low drive and Derby did not get another chance as good as that.
When Grant dropped McVeigh's 52nd minute cross Fleming put away the loose ball from 16 yards to leave Derby chasing shadows.
Damien Francis almost added a second and McVeigh rattled the bar before centre-half Malky Mackay headed the decisive goal in the 78th minute.
McVeigh's free-kick to the back post was headed back across goal by Mackay and inside Grant's right-hand post.
McVeigh got the third three minutes later with a neat finish from eight yards out after Gary Holt played the ball in from the Derby right and there was more misery to come for the home side.
Leon McKenzie had been a threat throughout and in the 88th minute his turn was too good for Youl Mawene, who hauled him down.
The penalty decision was a formality and McKenzie sent Grant to his left before rolling the spot-kick to the keeper's right to complete a happy day for Norwich and a miserable one for Derby.