SHEFFIELD United twice held the lead only to fall to substitute Wes Hoolahan's second-half hat-trick as Norwich City won for the fourth time in five games.
Andy Reid, on loan from Sunderland, fired Sheffield United – who have now lost on their last five visits to Carrow Road – ahead in the 17th minute with a fantastic 25-yard free-kick but defender Michael Nelson headed Norwich level within three minutes.
Richard Cresswell, on his return from suspension, put United back in front on 29 minutes but Norwich replied for a second time in the 64th minute when Hoolahan converted from the penalty spot.
Hoolahan grabbed Norwich's third with six minutes left with his second spot-kick conversion after Kyle Bartley was penalised by referee Phil Crossley for handball.
The Blades finished the game with 10 men after Stephen Quinn was sent off for violent conduct for a bad foul on Hoolahan, who scored a third in stoppage time.
United caretaker manager John Carver took exception to referee Crossley's decision-making.
He said: "It's not just one decision I'm upset about there were at least six of them.
"They are the sort of decisions that can cost people their jobs and send supporters, who have travelled more than four hours to get here, home unhappy.
"I had my say on the pitch in a controlled manner and then waited the 30 minutes before sitting down and discussing the incidents with the referee. I think one or two things will come out in the next few days."
The visitors made a bright start and Reid saw an early volley from 20 yards saved by City goalkeeper John Ruddy.
But he beat Ruddy on 17 minutes when Jens Berthel Askou was penalised for a foul on Ched Evans and from the free-kick, Reid curled the ball into the top corner for his first goal in six games.
However, the Canaries got themselves level within three minutes. Fox delivered a free-kick, after Nick Montgomery fouled Chris Martin, and Nelson headed home from six yards.
The Blades regained the lead in the 29th minute through Cresswell, who struck home from 12 yards after good work from Quinn.
The Irish midfielder pulled the home side level for a second time in the 64th minute. Montgomery brought down Grant Holt, and was booked, Hoolahan making no mistake from the spot.
Evans unleashed a shot from 35 yards which was comfortably dealt with by Ruddy and Steve Simonsen made a fine save from Martin at the other end.
Yeates fired over from 18 yards and Evans blazed over when well placed for United. But Hoolahan pounced with his second penalty and there was still time for Quinn to see red. Hoolahan wrapped up the points, and his hat-trick, on the breakaway.
Norwich City: Ruddy, Russell Martin, Nelson, Berthel Askou, Lappin, Korey Smith, Crofts, Fox (McNamee 61), Jackson (Hoolahan 46), Holt, Chris Martin, McNamee (Whitbread 88). Unused substitutes: Rudd, Drury, Johnson, Tudur Jones.
Sheffield United: Simonsen, Calve (Bogdanovic 87), Nosworthy, Bartley, Lowton, Yeates, Montgomery, Quinn, Reid, Evans, Cresswell. Unused substitutes: Wright, Ertl, Williamson, Ward, Kozluk, Batth.
Referee: Phil Crossley (Kent).