The Gunners appeared to be coasting to victory on Sunday on the back of goals either side of half-time from Theo Walcott and Mikael Silvestre.
But after a run of eight defeats and a draw in the league against Arsenal, Wigan added to their maiden wins over Chelsea and Liverpool this season as Ben Watson, Titus Bramble and Charles N’Zogbia conjured an astonishing comeback.
The remarkable result leaves Wigan seven points clear of the drop zone and seemingly safe, whereas Arsenal can now kiss goodbye to any hope they had of the title after back-to-back defeats in the space of five days.
Tottenham’s victory over leaders Chelsea on Saturday had given the visitors a glimmer of hope on the title front, but that has now evaporated, and they have only themselves to blame for a late collapse.
For 40 minutes here, they found themselves frustrated by a Wigan side desperate for points in their battle to stay in the top flight for a sixth successive season.
After being booed off the pitch on Wednesday following a goalless draw against an already-relegated and understrength Portsmouth side, Wigan were determined to restore the faith of their fans.
There was certainly an urgency about Roberto Martinez’s side, but for 80 minutes they lacked a cutting edge.
Instead it was Arsenal who were in the ascendancy, initially in the 41st minute as Nicklas Bendtner split covering defenders Maynor Figueroa and Bramble with a through ball of pace and precision.
After riding Bramble’s challenge and pulling away from Figueroa, Walcott then slid the ball underneath the advancing Chris Kirkland for his seventh goal of the season.
It was deserved as Walcott should have scored minutes prior to that after Abou Diaby had released him in behind Wigan’s defence.
Although left with a one-on-one opportunity with Kirkland just outside the six-yard box, he opted to try and find Bendtner with a square ball, only to pull it behind him, allowing Wigan to clear.
Walcott could, and perhaps should have given Arsenal a two-goal cushion on the stroke of half time, only to narrowly clear the bar with a rising drive from just inside the area.
Prior to Walcott’s opener Wigan were lively, but barely troubled Lukasz Fabianski, playing in his first league game since the end of last season with Manuel Almunia out with a wrist injury.
N’Zogbia, rumoured to be a target for Wenger in the summer, was narrowly wide with one curled effort, whilst a low, powerful 20-yard drive was straight at the Pole.
As a contest, it seemed to turn inside the opening three minutes of the second half, initially after just 40 seconds as Wigan were denied a penalty.
Referee Lee Mason, who had incurred the wrath of the Wigan fans all afternoon with his decisions, infuriated the locals further by turning a blind eye to Samir Nasri’s pull on the arm of Watson.
Moments later, and from Arsenal’s first attack of the half, Kirkland superbly denied Diaby at close range, with the ball eventually running for a corner.
Nasri proceeded to deliver an outswinger to which Wigan’s defence were guilty of falling asleep, allowing Silvestre an unmarked header from the penalty spot beyond Kirkland’s outstretched grasp.
Starting for Thomas Vermaelen, who misses the end to the season with a calf strain, it was Silvestre’s first goal for a year since a 4-1 win on this ground.
Wigan, though, did not roll over and die.
N’Zogbia first curled a tame effort that was easy pickings for Fabianski, on his 25th birthday, after being played in by Watson.
Watson was then denied by Fabianski who was at full stretch to prevent a low 20-yard shot from creeping inside his right-hand post, whilst Hugo Rodallega saw his scuffed shot trickle inches wide.
Then 10 minutes from time Watson hauled Wigan back into the game with a sidefoot effort from 12 yards after substitute Victor Moses had played the midfielder in from the bye-line.
It was the catalyst for the comeback, aided by a howler from Fabianski who fluffed an N’Zogbia corner, allowing Bramble a free header which crossed the line, despite Clichy’s efforts to hook the ball clear.
Then in the first of four minutes of added time N’Zogbia struck a sublime curling winner in off the post from 20 yards to send the majority of the DW Stadium into raptures, and leave Arsenal’s followers sickened.