United's hopes of progressing to the Carling Cup quarter-finals were ended by Arsenal's slick young Gunners.
On Hallowe'en, it wasn't ghosts that had the Blades running scared but Arsenal's latest crop of talent. Brazilian-born Croatian Eduardo netted a brace and Denilson was also on target at Bramall Lane.
With the respective leagues obviously of greater importance, both managers opted to use the fourth round tie to give squad players a run out. Bryan Robson made seven changes for the visit of the Premiership leaders.
Within 60 seconds a long Bromby throw caused problems in the Arsenal box and a flick-on by Morgan almost found Sharp, who was denied by the fingertips of Fabianski on three minutes after Lucketti had headed down a free-kick.
After the early endeavours it became apparent that Robson had returned to an orthodox 4-4-2 but the system could not prevent the visitors taking the lead with their first effort. From a Song pass out of defence, Bendtner found strike-partner EDUARDO, who moved the ball out of his feet and hammered a powerful left-foot shot from the edge of the box past Bennett's right hand and into the top corner.
The first threat of Walcott arrived on 11 minutes when he worked himself some space on the right but he opted to lay off instead of shooting and the move ended with Denilson looping a shot over the crossbar.
Carney showed encouraging early signs and he shot across goal and wide after cutting in from the right on 16 minutes but Arsenal's crisp passing was causing problems. Diaby's run through the heart of United's team created the space for Walcott but his shot from the right was skewed off target.
In a rare attack Stead's overhead kick, despite being off balance, caused a moment of panic in the Arsenal defence on 39 minutes and twice Fabianski opted to punch when under little pressure.
Late in the half United forced Arsenal back and a good move involving Carney and Quinn was ruined when Bromby's cross flew over the bar. In the one added minute at the end of the half a free-kick from the visitors saw Bennett quickly off his line to deny Walcott.
The Blades goalkeeper, however, could do little with Arsenal's second, five minutes after the interval. A pass from left-back Gibbs dissected United's central defenders and EDUARDO raced to the edge of box unopposed before slotted past the exposed Bennett.
Two minutes later a good move came close to halving the deficit. Carney and Bromby were involved before Montgomery delivered a cross and Stead got ahead of Song but the striker was unable to keep his effort down.
Just after the hour mark Robson made a double change but the Gunners were soon back on the attack. On 65 minutes, Bendtner pushed the ball forward and Walcott's pace got him in ahead of Armstrong, but he could only strike the base of a post from a narrow angle after going around Bennett.
Arsenal did add a third, however, on 69 minutes. DENILSON picked up the ball in midfield and was allowed to progress to the edge of the penalty area before striking a shot that deflected off Morgan, which helped beat Bennett.
United attempted to hit back straight away and went close after being awarded a free-kick on the left. Quinn's delivery was flicked on to the back pos where Lucketti took a touch before shooting and although the goalkeeper was beaten, Gilberto diverted the ball away for a corner.
Eduardo was denied a third when Armstrong deflected an effort over on 77 minutes and Diaby curled over from 25 yards.
The closing minutes were incidental. Arsenal blooded a couple more youngsters and Denilson tried his luck again from distance, this time firing wide on 89 minutes.
Three minutes of injury-time was the signal for three of the Lane stands to empty, whilst the travelling Gunners continued to sing and applauded their team at the final whistle, as did the Unitedites who remained in the ground.
Blades: Bennett, Bromby, Morgan, Stead (A. Quinn 62), Carney, Montgomery, Tonge (Gillespie 74), Armstrong, Lucketti, Sharp, S. Quinn (Webber 62).
Unused: Kilgallon, Gerrard.
Arsenal: Fabianski, Diaby (Merida 88), Diarra, Eduardo (Barazite 85), Denilson, Song, Gilberto, Bendtner, J. Hoyte, Walcott (Lansbury 83), Gibbs.
Unused: Mannone, G. Hoyte.
