And more importantly from Wigan's point of view, it was a win that moved them out of the bottom three and was richly deserved as their traditional late-season improvement gathers considerable momentum.
Martinez on 'historic moment'
United looked to have opened up a decisive gap over City during the Easter period - but this was a listless, almost complacent performance that on occasions reduced manager Sir Alex Ferguson to visible anger in his technical area.
They still hold an important advantage over neighbours City - who also brought about a five-goal swing in goal difference with their win - but this was a timely and painful reminder that significant work remains to be done before a 20th title can be confirmed.
It was a display epitomised by Wayne Rooney's poor performance before he was removed by Ferguson midway through the second half, even as United desperately sought an equaliser.
Wigan boss Roberto Martinez demanded a "perfect" performance from his team after feeling they were denied at least a point by poor officiating in the defeat at Chelsea. And after winning at Liverpool and beating Stoke City recently, his side produced another outstanding display.
Martinez felt his side were victims of another injustice when Victor Moses's header was ruled out for a foul on United keeper David de Gea in the first half - although they escaped themselves when Maynor Figueroa's late handball from Phil Jones's cross was missed by the officials.
Did you know?
Wigan had lost all 14 previous meetings with Manchester United
United failed to score for the first time in 18 games in all competitions
United's last defeat in the league came 13 games ago - on 4 January - against Newcastle
The victory moves Wigan out of the bottom three for the first time since 2 October
In the end United could have no serious complaints as a run of eight successive league victories came to a close with their first defeat at DW Stadium.
For the hosts, there is now the real hope of staging another escape from relegation after a season of struggle.
Paul Scholes was rested by the visitors after inspiring their win against QPR on Sunday - and the order and composure he has brought to their play since coming out of retirement was sorely missed in an awful first-half display.
Ferguson stalked his technical area furiously throughout and gestured angrily at Rooney when he tamely lost possession in a midfield tussle. The message was not well received by Rooney, but was nonetheless very clear.
The Latics were making all the running without seriously troubling United keeper De Gea until that hotly contested moment just before the half-hour after Moses headed in Jean Beausejour's corner.
The celebrations were cut short by the flag of assistant referee David Richardson, who ruled that Gary Caldwell had impeded De Gea. The decision sparked furious scenes as Martinez made his displeasure clear to the fourth official.
Displeasure will also have been in evidence inside the champions' dressing room at half-time as Ferguson reacted to his side's performance by removing Ashley Young and sending on Tom Cleverley, who enjoyed a successful loan spell at Wigan last season.
Wigan were better team - Ferguson
It made no immediate impact, however, and Wigan finally got the goal their endeavour and enterprise deserved after 50 minutes. Maloney worked a short corner routine with Beausejour before curling a perfect right-foot finish beyond the stretching De Gea.
Rio Ferdinand was clearly unimpressed with Rooney's part - or lack of it - in defending the corner - which replays showed should have been a goal-kick to United - and remonstrated with his colleague.
United had made no impression on Wigan's defence, leaving Ferguson no option but to ring the changes. Danny Welbeck replaced Javier Hernandez then, more surprisingly, Nani replaced Rooney after 65 minutes.
If Wigan were furious about Moses's disallowed goal, their opponents had cause for complaint with 18 minutes left when Figueroa looked to have clearly handled a Jones cross, but referee Dowd and his assistant Richardson were unmoved.
As United finally got up a head of steam, Wigan keeper Ali Al Habsi saved well from Welbeck but Moses was still proving a real handful as he forced De Gea to block with his legs then saw a shot deflected just wide.
United could not even stage their usual grandstand finish and at the final whistle the DW Stadium was awash with renewed belief that Wigan's survival bid will end in success.
Full Time The final whistle goes and the game is over.
Short corner taken by Mohamed Diame from the left by-line.
Danny Welbeck is flagged offside by the assistant referee. Indirect free kick taken by Gary Caldwell.
Free kick awarded for a foul by Antonio Valencia on Jean Beausejour. Ali Al Habsi takes the free kick.
Shot from just outside the area by Michael Carrick goes over the bar.
The ball is crossed by Luis Nani, Gary Caldwell manages to make a clearance.
Michael Carrick takes a shot. Gary Caldwell gets a block in.
Foul by Conor Sammon on Jonathan Evans, free kick awarded. Free kick taken by Rio Ferdinand.
Free kick taken by Ali Al Habsi.
Booking Booking for Phil Jones.
Phil Jones challenges Maynor Figueroa unfairly and gives away a free kick.
Danny Welbeck takes a shot. Save by Ali Al Habsi.
Jean Beausejour gives away a free kick for an unfair challenge on Tom Cleverley. Tom Cleverley restarts play with the free kick.
Mohamed Diame takes a shot. Blocked by Rio Ferdinand. Victor Moses takes a shot. Ryan Giggs gets a block in. Corner taken by Jean Beausejour.
Victor Moses takes a shot. Save by David De Gea.
Shot by Luis Nani from outside the box goes over the target.
Free kick awarded for an unfair challenge on Luis Nani by Emmerson Boyce. Free kick taken by Ryan Giggs.
Antonio Valencia delivers the ball, clearance made by Antolin Alcaraz.
Substitution Conor Sammon comes on in place of Shaun Maloney.
A cross is delivered by Ryan Giggs, clearance made by Maynor Figueroa.
Phil Jones crosses the ball, Mohamed Diame gets a block in. Inswinging corner taken left-footed by Ryan Giggs played to the near post, clearance by Mohamed Diame.
Inswinging corner taken left-footed by Ryan Giggs, Ali Al Habsi makes a save.
Luis Nani restarts play with the free kick.
Substitution Mohamed Diame joins the action as a substitute, replacing Franco Di Santo.
Free kick awarded for a foul by Shaun Maloney on Danny Welbeck.
Tom Cleverley delivers the ball, save by Ali Al Habsi.
Substitution (Man Utd) makes a substitution, with Luis Nani coming on for Wayne Rooney.
Jonathan Evans gives away a free kick for an unfair challenge on Shaun Maloney. Direct free kick taken by Antolin Alcaraz.
Substitution Danny Welbeck is brought on as a substitute for Javier Hernandez.
Unfair challenge on Tom Cleverley by Shaun Maloney results in a free kick. Michael Carrick takes the free kick.
Franco Di Santo takes a shot from 35 yards and went wide left of the goal.
Wayne Rooney produces a right-footed shot from just outside the area that goes harmlessly over the bar.
Assist on the goal came from Jean Beausejour.
49:39 Goal scored
Goal! - Shaun Maloney - Wigan 1 - 0 Man Utd Shaun Maloney finds the net with a goal from just outside the box to the top right corner of the goal. Wigan 1-0 Man Utd.
Shaun Maloney takes a short corner.
Antonio Valencia concedes a free kick for a foul on Shaun Maloney. Jean Beausejour takes the direct free kick.
Foul by Antonio Valencia on Jean Beausejour, free kick awarded. Maynor Figueroa restarts play with the free kick.
Franco Di Santo takes a shot. Blocked by Jonathan Evans.
Unfair challenge on Jean Beausejour by Ryan Giggs results in a free kick. Gary Caldwell takes the free kick.
The referee starts the second half.
Substitution Tom Cleverley comes on in place of Ashley Young.
45:00 +1:16 Half time
Half Time The players leave the pitch at half time.
Effort from long range by Wayne Rooney goes wide right of the target.
Franco Di Santo sends in a cross.
Franco Di Santo fouled by Phil Jones, the ref awards a free kick. Free kick taken by Jean Beausejour.
Foul by Javier Hernandez on Gary Caldwell, free kick awarded. Direct free kick taken by Antolin Alcaraz.
Free kick awarded for an unfair challenge on James McArthur by Ryan Giggs. Maynor Figueroa takes the free kick.
Victor Moses takes a shot. Blocked by Rio Ferdinand. Corner taken right-footed by Shaun Maloney. Gary Caldwell concedes a free kick for a foul on David De Gea. David De Gea restarts play with the free kick.
The official flags Victor Moses offside. David De Gea takes the free kick.
Foul by Wayne Rooney on James McArthur, free kick awarded. Jean Beausejour takes the free kick.
Booking Booking for Franco Di Santo.
Gary Caldwell takes the direct free kick.
Booking Jonathan Evans booked for unsporting behaviour.
Jonathan Evans concedes a free kick for a foul on Franco Di Santo.
The assistant referee flags for offside against Victor Moses. Rio Ferdinand takes the free kick.
Long range effort by Maynor Figueroa goes harmlessly over the crossbar.
Inswinging corner taken by Ryan Giggs from the right by-line, Phil Jones produces a header from close range which goes wide of the left-hand post.
Ryan Giggs concedes a free kick for a foul on Franco Di Santo. James McArthur restarts play with the free kick.
Antonio Valencia is flagged offside by the assistant referee. Gary Caldwell takes the free kick.
James McArthur concedes a free kick for a foul on Wayne Rooney. Michael Carrick takes the free kick.
Shaun Maloney produces a cross, Jonathan Evans manages to make a clearance.
Shot by Javier Hernandez from 20 yards. Blocked by Gary Caldwell.
Foul by Franco Di Santo on Jonathan Evans, free kick awarded. Free kick taken by David De Gea.
Jean Beausejour has an effort at goal from deep inside the area missing to the right of the goal.
Short corner taken by Shaun Maloney from the left by-line, James McCarthy takes a shot. David De Gea makes a save. Inswinging corner taken from the left by-line by Shaun Maloney, save by David De Gea.
Corner taken by Shaun Maloney from the left by-line, Phil Jones makes a clearance.
Unfair challenge on Jean Beausejour by Antonio Valencia results in a free kick. Jean Beausejour restarts play with the free kick.
Free kick awarded for an unfair challenge on Shaun Maloney by Michael Carrick. Direct strike on goal from the free kick comes in from Shaun Maloney.
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