WIGAN Athletic were left choking on a sense of injustice after copping a couple of real refereeing blunders at Chelsea.
A stoppage-time strike from Juan Mata broke the hearts of a Wigan side who had themselves been pushing for a winning goal such was the quality of the performance.
The fact Mata, who bundled home from close range after substitute Fernando Torres had hit the post, was offside in the build-up merely rubbed salt into the wounds.
Branislav Ivanovic had earlier opened the scoring on the hour mark from an even more blatantly offside position - a flashpoint that saw all 11 Wigan players surrounding linesman Dave Bryan on the near side to protest.
Referee Mike Jones backed the judgement of his assistant and gave the goal, but Latics showed their resolve to get up off the deck and back on level terms through Momo Diame eight minutes from time.
As the game entered added time - and with Latics sitting in 16th position in-play - skipper Gary Caldwell charged up field to try to net a winner, only to lose possession inside the Chelsea six-yard box.
And there was a depressing sense of inevitability as the Blues went right up the other end within seconds, for Mata to grab an undeserved winning goal.
It was particularly harsh on Ali Al Habsi, who had produced a number of stunning saves to keep out Chelsea, and certainly did not deserve the late sting in the tale.
The result leaves Wigan in the bottom three but in a slightly better position given surprising three-goal defeats to relegation rivals Bolton and Blackburn.
And Roberto Martinez will be confident that if the side can maintain this level of performance, safety is well within their grasp.
Martinez had named the same side for the fourth game in a row, although he was able to welcome back Diame to the bench after a groin problem.
Chelsea, with perhaps one eye on upcoming challenges in the FA Cup and the Champions League ahead, left out John Terry, Ashley Cole and Frank Lampard.
With one defeat in their last eight outings, Latics were entitled to come in with a reasonable amount of positivity as they looked for only their second victory at Stamford Bridge.
Franco di Santo, returning to his former stomping ground, received a huge cheer from the home fans as his name was read out, and the Argentine had the first shot of the game.
However, his effort from fully 25 yards was way off the mark and Petr Cech was able to watch it fly past the post.
Latics then worked a nice short corner resulting in Shaun Maloney finding himself inside the box and in space.
But his pull-back failed to find Jean Beausejour and the chance had gone.
At the other end, Antolin Alcaraz stood strong and timed his tackle well to dispossess Didier Drogba, who then failed to find the mark with a header from a Mata free-kick moments later.
Despite the home side needing to win to keep alive their hopes of a Champions League finish, Latics were enjoying a relatively comfortable opening quarter.
Their success in keeping the home side at arm’s length were evident when Gary Cahill advanced from the back and elected to try his luck from fully 35 yards.
The strike was sure and needed a great fingertip from Al Habsi to see it over the crossbar.
Victor Moses was seeing plenty of the ball and, after making the wrong decision on a couple of occasions, strode down the midfield and forced Michael Essien to bring him down at the expense of the game’s first booking.
The free-kick was played short by Caldwell to Maynor Figueroa, who tried his luck from similar distance only to fire straight at Cech.
Moses was the next to have a sight of goal, after a slip by rookie Ryan Bertrand, but again the shot was stright down Cech’s throat.
The home fans were starting to get frustrated as their team struggled to assert its dominance, and Drogba showed his danger by wriggling free of Caldwell and firing just wide of Al Habsi’s far post.
Maloney was also showing good touches on the ground he scored his last two goals for Aston Villa back on Boxing Day 2007.
And the Scot thought he’d won a penalty for his side just before the half-hour mark when he got to the byline and his pull-back appeared to strike the arm of David Luiz.
Referee Jones, however, pointed for a corner, which was headed just over by Caldwell.
Jones further infuriated Latics by either missing or refusing to recognise a clear trip by Bertrand on Emmerson Boyce, although he did redress the balance at the other end when Drogba seemed to be pulled by Caldwell inside the box only for play to go on.
After a brief rally, Latics were back on top and only a timely last-ditch challenge by Cahill stopped Di Santo in his tracks.
But the end-to-end nature of the game was shown when Chelsea went right up the other end and Mata showed magical footwork to work an opening for himself.
Thankfully for Latics, Al Habsi pulled off a fantastic block, with Figueroa clearing Drogba’s follow-up header off the line.
Raul Meireles was then lucky not to have his name taken for a similar trip on Moses that had seen his team-mate Essien carded, before Latics almost played themselves into trouble right on half-time.
Alcaraz busted a gut to support a break by Di Santo, who ignored his colleague and lumped a poor cross towards the far post that was gobbled up by Cech.
In a flash, the Blues were on the attack, with Alcaraz caught hopelessly out of position, and it took sensible play by James McCarthy and James McArthur to drop back and fill in that kept the scoreline blank.
Nevertheless, Latics were good value for being on level terms at the break, and they started the second stanza in a similar vein.
Beausejour scampered away down the left, and his cross almost found the onrushing Boyce at the far post.
Florent Malouda then became the second Chelsea man into the book for a late tackle on McCarthy in the centre circle, before Chelsea almost broke the deadlock.
Again it was Drogba who threatened, after great play by Essien, but the Ivorian’s shot was superbly blocked by the body of Al Habsi.
That was the cue for Roberto di Matteo to make his first move, withdrawing Malouda and sending on Torres to partner Drogba in attack.
And the home side had the lead within two minutes - via a hotly-disputed goal.
Meireles lobbed the ball in from the left and the whole Latics defence moved up to leave Ivanovic at least a couple of yards offside.
For some reason, though, the flag stayed down, the right-back stabbed it home and - despite vociferous protestations from the entire Wigan team - the goal was allowed to stand.
With the feeling of injustice still in the air, Latics kicked off and were almost level within a minute.
Moses broke through and was half-stopped by Bertrand, the ball falling to Di Santo 12 yards from goal.
With Cech out of position, Di Santo fired at goal and saw his shot blocked by Ivanovic of all people on the line.
They say things happen in threes, and Wigan’s afternoon was summed up moments later when Figueroa won the ball cleanly on halfway before being clattered by Torres, only for the official to bizarrely award Chelsea the free-kick and take the name of the grounded Honduran.
Martinez then made his move by sending on Diame and Ben Watson for Beausejour and McArthur, with Jon Obi Mikel replacing Essien for Chelsea, before Conor Sammon took over from Di Santo for the last 10 minutes.
Diame would have had a point to prove having missed the last two games with injury, after blowing great chances to score winning goals in the previous two games against West Brom and Norwich.
And the Senegal international marked his return to the first team in some style within moments.
With Latics enjoying more and more possession in the Chelsea half, Diame picked up the ball just outside the penalty area.
He won himself a yard by dragging the ball on to his left foot, and his shot flashed past Cech into the bottom corner before the goalkeeper could move.
Salomon Kalou replaced Sturridge for a deflated Chelsea, before Latics engineered a great chance to win it with five minutes remaining.
Moses got free down the left and his cross was deflected away from Sammon on the far post, the officials somehow awarding a goal-kick to Wigan’s collective disgust.
With four minutes of added time on the board, there was time for either side to win it.
And it looked like Latics were the team most likely when Watson crossed to the far post and found the unlikely figure of Caldwell totally unmarked.
Instead of heading for goal, however, the skipper tried to bring the ball down, and was robbed as he tried to apply the finishing touch.
And with the skipper 95 yards from his own goal, Chelsea broke away to break the hearts of the visitors in cruel fashion.
Diame crucially failed to foul a galloping Mata, and Torres found himself in acres of space on the far post.
Although the Spaniard’s shot struck the far post, the ball was bundled in by Mata with virtually the last kick - with Latics again receiving no assistance from the man with the flag.
Latics: Al Habsi 9; Alcaraz 8, Caldwell 8, Figueroa 8; Boyce 7, McCarthy 8, McArthur 7, Beausejour 7; Moses 8, Maloney 7; Di Santo 7.
Subs: Kirkland, Stam, Diame (for McArthur, 71), Watson (for Beausejour, 71), Gomez, Crusat, Sammon (for Di Santo, 80).
Chelsea: Cech; Ivanovic, Luiz, Cahill, Bertrand; Sturridge, Essien, Mata, Meireles, Malouda; Drogba.
Subs: Turnbull, Bosingwa, Ferreira, Mikel (for Essien, 74), Romeu, Kalou (for Sturridge, 84), Torres (for Malouda, 59).
Star Man: Ali Al Habsi - Pulled off a series of stunning saves and only beaten by two clearly offside goals.