United, looking far more hungry than Championship rivals Derby County on Saturday, came out firing on all cylinders and were 2-0 up inside 11 minutes through Billy Sharp and a Jon Stead corker.

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And only some superb stops by former Forest youngster Gamble prevented the Blades racing away with it.

However, Mark Stallard put Stags back in the contest on 21 minutes and Michael Blackwood had an effort disallowed that would have levelled matters.

But, unsurprisingly, United, who play three levels above Mansfield, were by far the better side and Alan O'Hare made a goal line clearance while Gamble continued to prove himself an excellent shot stopper until a Billy Sharp penalty in the last minute finally beat him to settle an entertaining pre-season friendly.

Stags restored Jason Lee to the starting XI. Also included were fellow trialists Gavin Hurran, new name Mark Abbott plus Michael Blackwood.

Blades sent a decent side down including Jon Stead, Sun Jihai, Lee Hendrie, Billy Sharp and Ugo Ehiogu.

Gamble saved bravely in the third minute as Sharp swung a boot at a ball allowed to bounce in the six yard box and the young keeper held on.

But the visitors stole a fortunate opening goal on seven minutes when a long ball down the left hit Sharp, then Silk and then bounced back into Sharp's path. He took it on and bundled a finish past Gamble.

Stags had made a sluggish start and should have been 2-0 down on 10 minutes as United struck both their posts in quick succession.

Stead was allowed too much space just inside the box and hit a low shot that came back off Gamble's right hand post. Hendrie followed up with an almost identical effort off the other upright and when the ball rolled back to him he struck another effort that Gamble parried.

But Blades had their reward in style a minute later as ex-Huddersfield and Sunderland star Stead turned 25 yards out to superbly find the top left hand corner with a top class finish that drew applause from the home fans too.

Armstrong out jumped Hurran to nod tamely at Gamble as United continued to pen Stags in their own half.

But they finally broke out on 18 minutes with Blackwood running at the defence before forcing Bennett to tip over his dipping 20 yard shot.

Arnold put over the corner and Somner met it with a glancing header at the near post that only just cleared the bar.

But Stags were back in the game with another deadly piece of finishing by Stallard on 21 minutes. Blackwood sent over a low cross right into the middle of the six yard box from the left and Stallard tucked it away first time.

More hesitant Mansfield defending gave Sharp another sight of goal on 26 minutes but he failed to even force the overworked Gamble into a save, curling over the top right angle.

A poor Gamble clearance left Hendrie a brief chance of lifting the ball into an empty net. But from 45 yards it was always going to be a huge task and it was easily blocked by the chest of O'Hare in the box.

Six minutes from the break Stead again tested Gamble with a powerful 15 yards shot towards the near post which the youngster was able to turn aside for a corner.

Stags survived that and three more though Naughton did force a flying save from Gamble to his left to keep out a blockbuster 25 yard effort after Stags had cleared the third of the flag kicks.

The young keeper was in fine form and had to produce a great reaction save to beat out a close range Stead header in stoppage time from Montgomery's left wing cross.

So, despite so many chances and so much possession for United, Stags went in still firmly in the game.

Mansfield began the second half again defending desperately under pressure from the lively and inventive visitors.

From Mansfield's first raid of the half on 55 minutes Blackwood thought he had levelled when he stooped to head home from Lee's flick only to see it ruled out for offside.

Quick thinking by Stallard saw him try to hoist a square pass from Robinson immediately over Bennett from 20 yards but he was too high.

Blackwood saw a fierce shot deflect wide for Stags while Armstrong curled a free kick wide of the post and Sharp was only just wide on the turn for the visitors as the score remained 2-1.

Hendrie had a shot blocked by O'Hare in the visitors' next threat and on 77 minutes the move of the match, a succession of one-touch passing, saw Hendrie just fail to crown it with a goal as he sent a low finish a foot the wrong side of the post from 18 yards.

Hurran was in the way of a Sharp shot and then O'Hare popped up to clear off the line on 79 minutes as Robertson beat Gamble with a first time sidefooted finish.

A great turn by Robertson took him into the box and straight in on Gamble only to se the keeper again make a great save.

However, United made the result certain in the final minute after Blackwood held onto Ehiogu at the far post and Sharp blasted a confident low finish past Gamble from the spot.

STAGS: Gamble, Silk, Abbott, Somner, O'Hare, Arnold (O'Connor 53), D'Laryea (Shaw 61), Stallard, Lee (Burrell 86), Blackwood (Hurst 72), Hurran. Subs: Robinson, Goward, McGhee, Wood, Trimmer.

BLADES: Bennett, Lowton, Stead (Robinson 59), Hendrie, Jihai (Quinn 80), Wedgebury, Montgomery, Armstrong, Sharp, Naughton, Ehiogu. Subs: Walker, Annerson, Law.

REFEREE: Mark Naylor.

ATTENDANCE: 2,432 (257 away).

CHAD STAGS MAN OF THE MATCH: Paddy Gamble.