NORWICH City's Premier League survival hopes took a hit as they were beaten 3-0 by direct rivals Sunderland at Carrow Road.
The visitors edged into a 41st-minute lead from the penalty spot after a tense first half, Fabio Borini converting from 12 yards after he was fouled by Andre Wisdom.
Jermain Defore then doubled their advantage eight minutes into the second half before Duncan Watmore added a third with the game stretched in added time.
City are still out of the bottom three in the table, but Sunderland are now just a point behind Alex Neil's side with a game in hand. City's next game is away to Arsenal in a fortnight's time.
Neil made one enforced change from the 1-0 defeat at Crystal Palace as Timm Klose (knee) missed out, with Sebastien Bassong stepping in for the Switzerland international.
A frenetic start saw both sets of players and staff come together in a melee on the touchline after just four minutes following Robbie Brady's push on DeAndre Yedlin.
Brady then had the Canaries' first shot on target two minutes later, but Vito Mannone comfortably kept out his effort on the turn from 20 yards.
City were the dominant side with Sunderland sloppy in possession, especially in defensive areas - but Borini went close for the visitors on 18 minutes when he flashed a shot wide from a narrow angle.
That preceded a promising spell for Sam Allardyce's team, but they had their 'keeper to thank on 26 minutes when Younes Kaboul diverted Brady's cross goalwards, with Mannone reacting well to make the save.
Martin Olsson - fresh from his winner against Newcastle a fortnight ago - then got the crowd on their feet with a stunning volley from all of 35 yards, but Mannone was equal to this one too.
The game was being played at a high-tempo, which meant that neither side had a steady flow of possession, especially as each were utilising a direct style in order to get up the pitch.
Four minutes before the break, however, Sunderland were given the chance to go in at half-time ahead when Wisdom tripped Borini in the area.
The Italian stepped up and finished calmly beyond Ruddy, giving the Black Cats a priceless advantage going into the break.
HALF-TIME: Norwich City 0-1 Sunderland
Nathan Redmond was introduced as a second half substitute for Norwich with Robbie Brady making way, and the winger was immediately involved in the action.
On 48 minutes, he picked the ball up in a central position 25 yards from goal and drilled a shot that deflected off the outside of the post and wide.
Five minutes later, however, Sunderland capitalised on hesitancy on the ball from Bassong to double their lead.
Jan Kirchhoff robbed the defender of possession before sliding in Borini, who picked out Defoe in the middle - and the veteran striker made no mistake from close-range.
Neil brought on Wes Hoolahan for Matt Jarvis with half an hour left, and City pressed valiantly to find a route back into the game.
Cattermole was leading by example for Sunderland, though - clearing twice off the line from Dieumerci Mbokani as Neil's team managed to get balls into the box, but it just wasn't dropping for them.
Cameron Jerome came on in Neil's final throw of the dice, but the Canaries didn't look like scoring with their opponents in control with their two-goal advantage.
In the final ten minutes, they upped the ante but crosses were running out for goal-kicks and shots were being deflected away from the danger-zone.
Sunderland rubberstamped their win in the final moments as Watmore took advantage of space in the area before beating Ruddy from a narrow angle.
FULL-TIME: Norwich City 0-3 Sunderland
GOALS: Black Cats: Fabio Borini (pen 41), Jermain Defoe (53), Duncan Watmore (90)
NORWICH CITY: Ruddy; Wisdom, Bennett, Bassong, Olsson; Jarvis (Hoolahan 59), Howson, O'Neil (c), Brady (Redmond 45); Naismith (Jerome 74); Mbokani. Subs not used: Rudd (GK), Dorrans, Mulumbu, Pinto.
SUNDERLAND: Mannone; Yedlin, Kone, Kaboul, Van Aanholt; Kirchhoff (O'Shea 85); M'Vila (Larsson 67), Cattermole (c); Khazri (Watmore 45), Borini, Defoe. Subs not used: Pickford (GK), Jones, N'Doye, Toivonen.
REFEREE: Andre Marriner