JAY Rodriguez headed a second-half winner to secure a 1-0 triumph over in-form Manchester United at Old Trafford - handing the Premier League title to rivals Manchester City.
Albion produced an organised, spirited and battling performance to shut out the hosts, who had won their last five successive league matches, and it was Rodriguez who nodded home the only goal of the game - his 11th of the season - in the 73rd minute.
The three points, Albion's first since mid-January, was deserved reward for first-team coach Darren Moore, who took charge of only his second first-team fixture against Jose Mourinho's side since being handed the reins last week.
It was Albion's third victory in their last five visits to United, tasting defeat only once in that period, and it proved enough to hand rivals City the league title.
Despite victory, Albion remain at the foot of the table heading into the final four matches of the season.
Mooro named an unchanged starting XI from the side who claimed a point against Swansea last weekend, although there was a place on the bench for fit-again Daniel Sturridge.
It was Albion who created the first clear-cut chance after 12 minutes, Rodriguez and Salomon Rondon combining to find Jake Livermore, who cut inside on to his left foot only to be denied low down by David De Gea.
The hosts saw penalty appeals waved away following Craig Dawson's challenge on Ander Herrera before Ben Foster spread himself well to deny former Baggies loanee Romelu Lukaku.
Albion stifled United throughout the first half and posed a threat themselves at the other end, Dawson's header back across goal from captain Chris Brunt's corner almost creating an opening just before the break.
Dawson made a crucial block at the start of the second half to deny United substitute Jesse Lingard.
Foster was then called upon to make a superb one-handed save in the 66th minute to keep out Lukaku's header as the hosts applied pressure in search of a breakthrough.
Lingard flashed an effort wide from distance before Albion silenced the home support.
Brunt's corner was headed back across goal by a combination of Dawson and Nemanja Matic and Rodriguez was on hand to head home from close range.
United looked to try and find an equaliser but the Baggies stood firm and claimed all the spoils.
ALBION: Foster, Nyom, Dawson, Hegazi, Gibbs, Phillips (Krychowiak 77), Livermore, Brunt (c) (Yacob 90+4), McClean, Rodriguez, Rondon (Sturridge 85).
Subs: Myhill, Gabr, Field, Burke.