The veteran defender, a free transfer from Bramall Lane in January, was only on the pitch because of injury to Ryan Taylor but when Phil Jagielka handballed the 33-year-old coolly drilled home to give his side a crucial 2-1 lead.Paul Jewell's side had taken a 14th-minute lead through Paul Scharner's left-foot volley but Jon Stead's header eight minutes before the interval put United in pole position to survive.
• Jewell jubilant
However, in a relegation race full of controversy following West Ham's escape with a #5.5million fine for irregularities over the signings of Carlos Tevez and Javier Mascherano there were a few more twists left and it was the Blades who suffered the deepest cut.
Substitute Danny Webber hit a post having beaten keeper Mike Pollitt in the second half and even the dismissal of Lee McCulloch for a second bookable offence in the 73rd minute could not save Neil Warnock's side.
In the first minute Lee McCulloch, playing just behind striker Emile Heskey, won a corner but when the cross came over Heskey could only balloon it over under pressure from Matt Kilgallon.
The Wigan players appealed for a penalty for a shove on the former England man but referee Mike Dean was unimpressed.
The relentless action was befitting of a relegation decider and Wigan continued to make all the early running, with Paul Scharner's speculative volley from 20 yards in the 11th minute floating wide of Paddy Kenny's right post.
It was a warning of what was to come as the deadlock was broken in the 14th minute.
Heskey picked out Kevin Kilbane on the left and his low cross was met first-time by Scharner from the edge of the penalty area and the ball flew past Kenny and into the net.
With West Ham at that point drawing against Manchester United the goal meant United and not Wigan occupied the final relegation place.
Scharner could have had another in the 23rd minute when Kilbane again fed Heskey, who drove into the area before crossing to the far post where the Austrian midfielder headed over.
Wigan suffered a huge blow in the 31st minute when captain Arjan De Zeeuw was forced off with what looked like a knee injury. He was replaced by Josip Skoko, which meant the dangerous Scharner had to drop back into defence.
But in the 37th minute the relegation picture changed again as United equalised - although it was not without cost to both sides.
Jagielka, playing at right-back, crossed from wide and Stead rose above the defence to head the ball past Pollitt.
The consequence of that was a sickening clash of heads between the goalkeeper and striker which resulted in both receiving lengthy treatment.
Right-back Taylor was also injured - more seriously than the rest - and he hobbled to the sidelines before being carried away on a stretcher.
Former Sheffield United defender Unsworth came on in his place.
The hosts could have had a penalty and a goal in the same incident in first-half injury time as McCulloch looked to have dragged Jagielka to the floor before Stead blazed wide from six yards.
Unsworth's first contribution was a late foul on Nade which earned a booking.
However, his second was more crucial as he drilled home a penalty late in injury time after Jagielka handballed an inswinging free-kick from the left by his former team-mate.
Warnock made an immediate change at the start of the second half, with Danny Webber replacing the injured Nade.
Kenny was first into the action, producing a superb one-handed save to deny Heskey's overhead kick from Denny Landzaat's corner in the 50th minute.
Bramall Lane was celebrating prematurely five minutes later when Stead's flick-on put Webber clean through and he poked the ball past Pollitt only to see it rebound back off a post.
Kilgallon had a half-chance in the 60th minute when Gillespie's long-throw was flicked on by Chris Morgan but his fellow centre-back could just not get over the ball.
The impressive Scharner then had to be alert to half-block a Stead shot after Michael Tonge's quickly-taken free-kick.
Morgan then rose highest to meet substitute Colin Kazim-Richards' corner but turned his header wide at the far post.
United were handed a glimmer of hope when the hard-working McCulloch was sent off in the 73rd minute for a second bookable offence after clattering into Tonge having been booked for dissent in the 55th minute.
United laid seize to the Wigan goal in the late stages, with Gillespie's right-wing cross grazing the crossbar and Tonge admirably staying on his feet in the penalty area when he could easily have gone down under a challenge.
Jewell jubilantManager Paul Jewell, who was palpably under pressure as he argued with officials
during five minutes of injury-time, was proud of his players.
'We played well, it was backs-to-the-wall stuff,' he said.
'We defended manfully - something we haven't always done this season.
'I always thought there'd be some twists and turns and it's an amazing
achievement.
'We've shown everyone, the so-called experts. I've forgotten more about
football than they've ever known.'
David Unsworth, who joined the Latics on a free from United in January, scored
the winner from the penalty spot after goals from Paul Scharner and Jon Stead,
and Jewell believes his display was exemplary.
'He was great. He epitomised us today. It was backs to the wall stuff and
it's been great.'
Sheffield United boss Neil Warnock admitted to feeling 'bitter' over the
circumstances surrounding his side's relegation from the Barclays Premiership.
Warnock claimed the West Ham situation, coupled with the decisions of
Manchester United and Liverpool to field weakened teams in recent weeks, made
his side's slide harder to take.
But Warnock clearly attempted to rein in the considerable anger he feels over
the situation, and said he expected any lingering furore to quickly disappear.
Warnock said: 'I am bitter about all the circumstances over the last two
weeks really but by Tuesday it will all be fish and chip paper. I have just got
to get over that bitterness.
'It is only human to look at the dossier and not understand why they (West
Ham) haven't had any point deducted and that is why you do get disappointed.
'But by Tuesday it will all be in the bin and there won't be a big hoo-haa.
Sheffield United - so what. West Ham are a big club with big reputations and
they've obviously got good solicitors.'
Of Sir Alex Ferguson's decision to start the likes of Cristiano Ronaldo and
Ryan Giggs on the substitutes' bench as his side lost 1-0 at home to West Ham,
Warnock added: 'I think I was sold a dummy earlier in the week.
'But Sir Alex has his own reasons and obviously the Cup final was more
important to him. But fate's fate. Probably Chelsea will win the FA Cup final
and AC Milan will win the Champions League.'
Warnock refused to be drawn on his own future and preferred to pay tribute to
his players whom he said had proved themselves worthy of their Premiership
status.
Describing relegation as a 'gut-wrenching, horrible feeling', Warnock added:
'All season we have not made it difficult enough for other teams and given
goals away when we have been in good positions.
'They haven't had to work hard for either goal today and we have committed
suicide really. The lads have been magnificent and tried their hardest and I
couldn't have got much more out of them.
'But it is still very disappointing when you go down because of the thickness
of a post.'
Wigan boss Paul Jewell expressed his sympathy for the Blades and reiterated
his anger at the West Ham affair, calling the time of the Premier League's
announcement 'scandalous'.
He added: 'The ideal scenario for the Premier League might have been for
Manchester United to beat West Ham and some people think West Ham have got off
the hook a little bit.
'But I don't want to go down that route. The reason we had to go into the
final game to stay up was that we weren't good enough over the 37 games
before.'
Jewell insisted he had never lost the belief that his side would survive
despite starting the day as big favourites for the drop as they had to win to
stand any chance.
He added: 'I have been in football for a long time and I know when people
have some doubts in their mind you have got to play on them.
'Sheffield United didn't have to win today to stay up but we had nothing else
in our minds but to win the game. I said to the players, they will be edgy
because it is all in their hands.
'I feel like I have just run a marathon. It is a great achievement for a club
of our size and we have had to overcome a lot of obstacles.
'People's persona of Wigan is that it is probably the least attractive club
in the Premiership so we deserve great credit for being there for a third
successive season.'
Sheffield United 1 - 2 Wigan Athletic
