Norwich returned to second in the Championship with a superb victory over local rivals Ipswich at Portman Road.
Andrew Surman opened the scoring with a tap-in after Arran Lee-Barrett parried Wes Hoolahan's cross.
Gareth McAuley inadvertantly touched in David Fox's corner before Simeon Jackson brilliantly converted Grant Holt's splendid delivery.
Jimmy Bullard reduced the deficit with a cracking drive before late strikes from Russell Martin and Danny Pacheco.
The resounding win meant the Canaries achieved their first double over the Suffolk club since the 2003/2004 season.
But, more importantly, Paul Lambert's team regained the initiative from Cardiff in the race for the Premier League and increased their hopes of a second successive promotion.
Cardiff are now two points behind the Canaries - but do have a game in hand.
The Bluebirds host Championship leaders QPR on Saturday in a key lunchtime match - which will be televised on BBC One and live on the BBC Sport website - with Rangers knowing a win will secure their own return to the top flight.
"We have personnel in the team that can make things happen," Lambert told BBC Radio 5 live.
"Having been promoted, we were just looking to survive this season. The supporters have been brilliant for us and they make a big, big difference. The spirit is good and there are top players here."
The Canaries finished third in the first Premier League season in 1992/93 but were relegated two seasons later. They regained their place in the top flight in 2004 but struggled and were relegated after finishing second from bottom.
Norwich were relegated again into League One in 2009 but, after losing their opening game at home 7-1 to Colchester, they rebounded in spectacular fashion, winning the title by nine points.
In Thursday's match, Norwich looked dangerous every time they broke forward but were also strong defensively against Paul Jewell's side, who had won four of their last five games going into the derby.
Ipswich produced a lacklustre performance in the first half but improved after the break.
Bullard was quiet but created the home side's best chances. He first caused Norwich nerves to twitch with a curling free-kick that went fractionally wide.
The former Fulham and Hull player then volleyed narrowly wide before finally hitting the mark 12 minutes from the end.
But any thoughts of a comeback were ended when full-back Martin slammed Norwich's fourth following a quick counter by Hoolahan before substitute Pacheco powered in the fifth in stoppage time.
The result leaves Ipswich in 12th, six points below a play-off place.