It had been difficult to find anything that was not stacked against Queens Park Rangers in this derby or their crusade to avoid the drop into the Championship. A couple of statistics stood out. They had not won at Stamford Bridge since 1983. And only one club that has entered New Year's Day at the foot of the Premier League table has avoided relegation.

The obstacles merely added gloss to a performance and result that will live long in the memories of every QPR fan that witnessed it, particularly if it can serve as the catalyst for a feat of grand escapology.

Harry Redknapp's team rode their luck at times, particularly during a Chelsea purple patch early in the second half. The visitors were indebted to the rugged quality of their defending and to the goalkeeper Júlio César, who made decisive interventions, none more eye-catching than his 52nd-minute stop from Fernando Torres. The unromantic reading of the evening had Chelsea being robbed. They had the chances to win and jump to third place. Their players departed in a daze.

QPR, though, saw a different script, one built on mental and physical toughness, a willingness to work for each other and rounded off by a fairytale winner from the former Chelsea winger Shaun Wright-Phillips, whose previous Premier League goal had come in May 2010 for Manchester City.

Oscar half-cleared a QPR corner to Adel Taarabt and the playmaker caressed his lay-off into Wright-Phillips' path and positively begged him to lash it first time for goal. The substitute obliged and his right-footed drive from outside the area was marked by such timing and power that it deserved nothing less than to swell the far corner of the net.

This was the classic game of two halves. The first was dire; the second absorbing and, ultimately, glorious for QPR. Redknapp talked of the victory having the capacity to alter perceptions, both within the club and outside it. Rival teams, he suggested, would look over their shoulders to note what was QPR's first away win in 24 league games and their first clean sheet away from Loftus Road since November 2011. Amid the post-match fervour in the QPR dressing room, the players felt the injection of belief.

Redknapp's team had even had to overcome the whiff of injustice in the third minute when Marko Marin, on his full Premier League debut for Chelsea, lunged in on Stéphane Mbia with the sort of late and high challenge that brings winces and gasps. The mark just below Mbia's knee suggested the challenge merited red rather than the yellow shown by Lee Mason but Redknapp absolved the winger of blame afterwards, when he also confirmed his interest in signing the former Chelsea defender Tal Ben Haim. "We will look to give him a contract until the end of the season," said the QPR manager.

Mason was the official who sent off QPR's Shaun Derry at Manchester United last season for the non-foul on Ashley Young and it was Derry who led the retribution against Marin. The midfielder's challenge was not quite a clothes line but the outstretched arm that collared Marin ought to have brought a booking. Derry escaped, as did Clint Hill when he went through the back of Marin in the second half.

Redknapp made changes from Sunday's dismal surrender against Liverpool, loading the midfield and asking Taarabt to sprinkle his magic as a false No9. He also lost Junior Hoilett early on to a hamstring pull, which paved the way for Wright-Phillips' introduction.

Chelsea's changes, though, drew some of the post-match focus, with Rafael Benítez forced to defend his decision to use Eden Hazard and Juan Mata as substitutes after the hour. Ashley Cole was left on the bench. The Chelsea manager argued it was physically impossible for his players to play every minute of every game.

The first half was cagey but QPR did not care, as they set up deep, pressed and scrapped for the result that could bring hope. Wright-Phillips sent a shot skidding wide on the break but otherwise, the pattern was established: Chelsea on the front foot, seeking to prise QPR apart.

David Luiz volleyed into the ground and over the crossbar; Torres's touch deserted him when he was well-placed and Oscar twice had sightings. His first shot deflected wide off Hill; the second ricocheted off Frank Lampard and forced César into a reaction save with his feet. Victor Moses lifted the follow-up over the bar. None of the chances, though, could be described as clear-cut.

The second half brought the drama. Chelsea improved, with Marin and Oscar showing quicksilver quality. Marin tricked past Derry and his low cross just eluded Moses while Lampard saw a shot deflected wide. Branislav Ivanovic also skimmed the top of the crossbar with a header.

The moment when Chelsea thought they had cracked it came when David Luiz's rocket hit Wright-Phillips to fall for Torres, eight yards out. César, though, blocked the blast unflinchingly. Chelsea were also left to rue the borderline offside decision that pulled back Lampard after he had shot into the far corner.

But QPR had their moments, not least when Taarabt's beautiful through-ball released Jamie Mackie, who was denied by Gary Cahill's saving tackle. Earlier, following a smart break from Wright-Phillips and Taarabt,

Esteban Granero's curling shot forced Ross Turnbull to save. Wright-Phillips' goal, though, sparked the delirium and, when Ivanovic's late flicked header drifted inches wide, QPR knew that it would be a famous night.