Roy Hodgson's side picked up a valuable win thanks to an excellent performance, with the former Ipswich man's goal condemning the west London side to defeat
The Baggies had the better of the first-half as they continuously pressed high up the pitch, affording Chelsea next to no time on the ball, but the visitors held firm with Petr Cech on form.
The second-half followed a similar pattern as the hosts dominated long periods and their goal finally came as McAuley poked home following a free-kick, as Andre Villas-Boas woes worsen at the west London club.
Both sides named unchanged teams from their respective wins last weekend as Fernando Torres missed out once again for Chelsea, while Daniel Sturridge also started despite being a doubt with a toe injury.
After five goals in his last two matches, Peter Odemwingie partnered Marc-Antoine Fortune up front, while Jerome Thomas started even though he was doubtful and Chris Brunt returned to the squad, taking a place on the bench.
The match started brightly for both sides as first Keith Andrews’ header almost tested Petr Cech, and then moments later at the other end Gary Cahill tried to bundle the ball home after Juan Mata’s corner, but the home defence stood strong.
The hosts weren't allowing Chelsea any freedom in possession as they pressed them with intent, and after robbing Ramires of the ball in the centre circle, the Baggies carved open another chance as James Morrison’s long-range effort was tipped over the bar by Cech.
The visitors were second best for the opening 15 minutes, but they soon got themselves a real chance. Michael Essien played a forward ball to Didier Drogba, who in turn flicked cleverly into the penalty area, but Mata’s right-footed attempt was turned behind by Ben Foster.
Next to try his luck was Fortune as his effort squirmed wide of Cech’s right-hand post, followed soon by a long-range strike from Odemwingie, which also went wide.
With Chelsea offering more in attack, West Brom continued to give as good as they got. Thomas looked particularly lively down the left-wing, beating Ramires easily time and time again, while Andrews went close with a header, but still there was no breakthrough.
The backwards and forwards nature of the match continued as Chelsea were twice unlucky not to take the lead. First, Essien’s driven strike was clawed away from the top corner by Foster, and then Sturridge, with the defence and goal at his mercy, beat the goalkeeper, but put his strike wide of the post. Despite a late effort from Youssouf Mulumbu, the first-half ended goalless.
The second period started in a similar to vein, as both sides traded blows, with neither team managing a goal.
Referee Mark Halsey received a massive cheer as he overturned his linesman’s decision to give the away side a free-kick, subsequently handing West Brom a set-piece from which they almost scored, but Odemwingie was crowded out by the visitors backline.
However, Chelsea went straight down the other end and almost took the lead themselves. Steven Reid gave possession away before going down injured, but the visitors weren’t interested as Drogba played Sturridge though the middle, only for Foster to run out of his goal by some distance - beating the striker and clearing.
Fortune soon got himself another opportunity as a ball from the left evaded Luiz, bouncing over the Brazilian, but the Baggies striker’s shot was palmed over by Cech. By now the match was fast and furious, with both goalkeepers regularly called into action.
West Brom really began to boss the match with around 30 minutes remaining, but Cech continued to thwart the hosts. Fortune was at the fore once again as he tested the keeper from the edge of the box, then moments later Ashley Cole cleared his lines just before Morrison could head home for the Baggies.
As the hosts continued to press, a goal always looked likely and they finally took the lead through McAuley. Chelsea once again failed to clear their lines from a West Brom free-kick and after the ball bobbled about in the penalty area, the former Ipswich defender was on hand to poke home past Cech.
Frank Lampard came inches from equalising as he flicked Mata's pass goalwards, but West Brom held on for the three points after a fantastic performance to crank up the pressure a further notch on Villas-Boas.
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