Chelsea's title dreams evaporated two minutes from time as Wigan deservedly snatched a point at the DW Stadium tonight.
Jordi Gomez slotted home from close range with two minutes remaining cancelling out Daniel Sturridge's brilliant second half strike.
It was a point the home side deserved and The Blues' title ambitions, weak at the start of the game now look all but over.
Wigan had an early shout for a penalty, on five minutes turned down when Ashley Cole and Jordi Gomez clashed inside the visitors' area.
But referee Martin Atkinson waved play on. Chelsea's first effort, two minutes later on goal came from right-back Jose Bosingwa, whose weak shot failed to trouble Ali Al Hasbi.
On 14 minutes, Terry, perhaps tired of the keep-ball but going nowhere possession, decided totals matters into his own hands when receiving the ball 30 yards out.
Rather than passing he let fly. Sadly for the Chelsea skipper, his effort resulted in a wayward effort that almost went off for a throw-in.
Raul Meireles decided to copyTerry but this time his effort was almost spot on. His excellent 25 yard volley, was arrowing on target, but I took a slight deflection, allowing Al Hasbi time to deflect the ball round his right post for a corner.
This sparked Wigan into a period of pressure, that while not worrying Petr Cech's goal did serve to put doubts into Chelsea wether their tippy-tappy football was the way town the game.
The growing confidence of the home side, who have not won a home game since August, saw Maynor Figueroa let fly from the edge of the Chelsea area, wide on the left.
The fierce ball swerved on the air, but away from Cech's goal, much to his relief.
Chelsea had a fine chance to take the lead with seven of minutes of the half remaining.
Excellent set-up play by Meireles saw his cross into area, met on the head by Drogba,
The Ivory Coast striker could only glance the header inches wide of Al Hasbi's right post.
Wigan's second shout for a penalty on 41 minutes was again turned down by Atkinson as Victor Moses long range shot went straight into the body of Branislav Ivanovic.
Wigan fans claimed handball, but they fell on the deaf ears of the referee.
Andre Villas-Boas decided that that team would never get thought Wigan's rearguard, so he made a change at half-time bringing on Salomon Kalou for Romeu.
Lampard moved back beside Meirles, bringing Kalou on the left, Sturridge on the right, with Mata just behind Drogba.
Moses really should have scored on 52 minutes when he received the ball inside Chelsea's area, but rather than taking a first-time shot he elected to hold possession eventually forcing him to take a wild, byline swipe that went hopelessly wide.
Drogba had a half-chance three minutes later when the striker stabbed the ball into the Wigan side-netting from close range after Kalou zipped down the byline before setting up his countryman.
On 59 minutes, and with Lampard off the pitch receiving treatment for a cut lip, the Blues decided it was time to score.
Ashley Cole, wide on the left sent in an inch-perfect long ball deep into Wigan's area. Sturridge collected the ball first time, wide on the left and arrowed a perfect, low, right-footed drive across Al Hasbi's path and into the far corner of his net.
Mikel replaced Mata on 66 minutes to bolster the midfield allowing Lampard to resume his top of the midfield diamond position.
To pep up their attack, Wigan boss Roberto Martinez replaced Conor Sammon and David Jones for ex-Chelsea striker Franco Di Santo and Hugo Rodaliega on 72 minutes.
And it almost worked within three minutes, a wayward Ivanovic back pass let in Di Santo whose goal-bound shot was gratefully headed clear by Mikel for a corner.
Villas-Boas's final substitution saw Florent Malouda enter the fray for Sturridge with 10 minutes remaining.
With two minutes remaining and Chelsea on the back foot, the home side equalised when Jordi Gomez had the easiest of chances to slot home from six yards into an unguarded net after excellent set up play by Di Santo.
Teams: Chelsea Cech, Ivanovic, Cole, Romeu, Lampard, Mata, Drogba, Meireles, Bosingwa, Sturridge, Terry Subs: Turnbull, Torres, Mikel, Malouda, Ferreira, McEachran, Kalou Wigan Athletic Al Hasbi, Alcaraz, McCarthy, Caldwell, Moses, Gomez, Sammon, Jones, Diame, Stam, Figueroa. Subs Pollitt, Gohouri, Crusat, Watson, Di Santo, McArthur, Rodallega.