A dramatic late equaliser by Jordi Gómez robbed Chelsea of two points just when an efficient if uninspiring performance seemed to have preserved their winning habit. In a pulsating game on a cold night and a wet pitch neither side truly deserved to lose, but Wigan will undoubtedly be more pleased with their point than Chelsea, who played well enough to put suggestions of disunity or unrest to bed but not well enough to close out the victory that Daniel Sturridge's splendid opening goal seemed to have earned.
"We just let it slip in the end," André Villas-Boas acknowledged. "But this is a different Wigan, they have picked up momentum from recent results. It's disappointing, but we have to put it behind us and focus on a massive game against Tottenham on Thursday."
Wigan have been showing signs of life of late, briefly climbing out of the bottom three as a result of back-to-back away wins at Sunderland and West Brom, though they have not won on their own ground since beating a still shaky Queens Park Rangers back in August. Picking up points against a Chelsea side beginning to look lean and businesslike again seemed a tall order.
"We frustrated Chelsea for most of the game," Roberto Martínez said. "It was disappointing to go behind. That was the only real piece of quality they produced and it led to their only shot on target."
Despite their lowly league position, the home side began with confidence and verve. Victor Moses tricked the Chelsea defence in the opening five minutes and Gómez had a penalty appeal against Ashley Cole turned down, probably correctly as he seemed to be seeking a decision rather than threatening the Chelsea goal. Wigan were somewhat oddly set up, with David Jones detailed to follow Daniel Sturridge and Mohamed Diamé only notionally operating on the right wing, leaving only Ronnie Stam regularly covering the flank where Juan Mata and Cole found unexpected freedom.
When Didier Drogba turned up in the wide open spaces on the left in the 12th minute it led to Chelsea's first attack of note, though ideally Drogba would have been in the middle to meet Mata's cross instead of the less imposing Sturridge.
Wigan were managing to keep Chelsea at bay. The visitors' best efforts of the first half-hour were a speculative shot from 25 yards by John Terry that flew narrowly wide and an effort from a similar distance by Oriol Romeu that Ali al-Habsi tipped round a post, though by the mid-point of the first half the home side were being penned in their own half and struggling to get hold of the ball.
For all Chelsea's control of the game they created very few chances, perhaps exhausted after their efforts in defeating Manchester City on Monday. Five minutes before the interval, Wigan were unable to close down Raul Meireles in time to prevent him crossing for Drogba at the far post, but the striker could only manage a stooping header that went the wrong side of the post.
Wigan's conviction that they were not getting any of the marginal decisions from Martin Atkinson increased when Moses saw a shot stopped on the line by Branislav Ivanovic. The referee immediately waved play on, despite a strong suggestion that the ball had hit the defender on the arm. Replays confirmed that it had, though it was not a raised arm and Ivanovic would have had difficulty getting out of the way.
The Wigan main stand gave Atkinson a spontaneous standing ovation when he finally blew for a foul on Moses minutes later. With the same striker narrowly failing to reach a Jones cross on the stroke of the interval in what was probably the first half's clearest chance, the home side could feel more than encouraged by reaching the break level. Moses continued to pose problems for the Chelsea defence in the second half with his control and tricky turns, even if his finishing and decision-making was not always as sound.
At one point he flicked the ball over two Chelsea defenders to leave himself with only Petr Cech to beat from inside the six-yard box, only to fire a volley that went out for a throw-in.
Drogba hit the side-netting with Chelsea's best chance after Salomon Kalou had escaped Antolín Alcaraz to skip to the goal-line, before the visitors finally opened up Wigan with a classy move to take the lead just before the hour mark.
Cole advanced to half way on the left and sent a diagonal ball forward to pick out Sturridge's run into the box from the opposite wing. Simultaneously bringing the ball down and getting goal-side of what little remained of Wigan's defensive cover, Sturridge managed a decisive finish to beat Habsi from a narrow angle.
The goal was all the more remarkable for coming at a stage when Chelsea were down to 10 men, Frank Lampard having temporarily left the field for treatment after being accidentally struck by Diamé.
Wigan kept to their task, Jones sending a shot over the bar and Maynor Figueroa bringing a save from Cech. Villas-Boas was sufficiently concerned to make a defensive substitution to protect what he had, replacing Mata with Mikel John Obi. Martínez responded by throwing on two more attackers in Hugo Rodallega and Franco Di Santo to chase the game, the latter bringing a sensational headed clearance off the line from Ivanovic after Cech had been caught out of position.
Never completely convincing, Cech was at fault again for the late equaliser, allowing Rodallega's shot to squirm out of his grasp for Gómez to sweep home.
It was nothing less than the home side deserved, even if Chelsea must have thought they had done enough to seal a victory. "We could have kept the ball better in the last moments," a resigned but fair Villas-Boas admitted. "But Wigan had the momentum by then and they got the goal and the point they deserved."