James Beattie's seven-minute hat-trick condemned 10-man Leicester City to a 3-0 defeat at Bramall Lane on Saturday afternoon.
The former Everton and England international striker netted in the 12th, 14th and 19th minutes with Foxes stand-in skipper Patrick Kisnorbo being sent off for what was adjudged a professional foul on Billy Sharp in the lead to Beattie's first goal.
The visitors did improve after the interval with Steve Howard and Matty Fryatt coming close but they were always left with an uphill task after Beattie's first-half cameo.
After a nervy start from both sides, Stephen Quinn headed well wide on six minutes before a last ditch tackle from Gary Naysmith a minute later denied Fryatt on the edge of the area.
However, the Foxes were dealt a cruel blow on 11 minutes when Beattie fired the home side in front after his initial spot-kick had been pushed on to the post by Paul Henderson.
Kisnorbo was adjudged to have brought down the advancing Sharp inside the area and after seeing his assistant referee put his flag across his chest, official Mike Pike pointed to the spot.
To make matters worse, the Australian international was dismissed for what was deemed a professional foul.
Beattie stepped up and saw his initial penalty tipped on to the upright by the Australian but the striker was first to react and smashed home the rebound from close range for the opener.
Beattie was at it again four minutes later when he doubled the Blades' lead with a powerful free-kick from 25-yards which an unsighted Henderson failed to stop - the ball squeezing in between him and his near post.
The Foxes attempted to hit back with Steve Howard coming close with his head from David Bell's corner.
But it got even worse for the visitors on 19 minutes when Beattie completed his quick-fire hat-trick, heading home unmarked from Michael Tonge's corner.
City's frustrations were clear for all to see and Richard Stearman was booked for a foul on Quinn a minute later.
James Wesolowski tried his luck from 20-yards in the 30th minute but saw his effort blocked by Ugo Ehiogu.
Stearman was forced to head over his own bar on 40 minutes after David Cotterill had swung in a teasing cross from the right.
Howard almost pulled a goal back for the Foxes two minutes later but saw his low drive creep agonisingly wide with Ian Bennett beaten.
The Blades keeper then saved from Matt Oakley's left-footed drive before Henderson raced off his line to deny Sharp in first-half stoppage time.
However, the damage had already been done as the home side went into the break three goals down.
City were first to show after the re-start with Bennett gathering at the second attempt from Howard's shot.
At the other end, Quinn shot wide on 51 minutes before Joe Mattock was fortunate to get away with a late tackle on Cotterill inside the area.
Beattie fired over in the 55th minute while David Bell tested Bennett a minute later.
John Halls was booked for a foul on Bell on the hour and from the resulting free-kick by Mattock, Howard headed over the bar.
The Foxes made a double change on 63 minutes with Andy King and James Chambers replacing Matt Oakley and Stearman respectively.
Fryatt squandered a golden opportunity to get his side back into the game in the 65th minute when, after some impressive work by Bell, he saw his shot saved by Bennett before putting the rebound over the bar with the goal gaping.
Goalscorer Beattie made way for Jon Stead on 66 minutes then Howard shot wide in the 72nd minute.
Teenager Harry Worley, a recent capture from Chelsea, came on for his debut in the 73rd minute, replacing Gareth McAuley.
Henderson got down well to cut out Cotterill's low cross on 78 minutes then Quinn headed wide from Halls' right-wing cross three minutes later.
Bennett saved from Howard again while a last gasp block from Chambers thwarted Stead.
Former Fox Keith Gillespie replaced Cotterill in the 86th minute before Nicky Law came on for Tonge two minutes from time.
However, the damage had already been done and despite an improved second half showing, City returned home pointless.
City: Henderson, Stearman (Chambers J 63), McAuley (Worley 73), Kisnorbo ©, Mattock, Bell, Oakley (King 63), Wesolowski, N'Gotty, Fryatt, Howard. Subs not used: Douglas, Laczko.
United: Bennett, Naysmith, Beattie (Stead 66), Cotterill (Gillespie 86), Speed ©, Kilgallon, Tonge (Law 88), Halls, Sharp, Quinn, Ehiogu. Subs not used: Carney, Geary.
Yellow Cards
City: Stearman (20)
United: Halls (60)
Red Cards
City: Kisnorbo (11)
United: None
Referee: Mike Pike (Cumbria)
Attendance: 24,818
