Manchester United's lack of cutting edge cost it again as West Brom earned a smash-and-grab 1-0 win at Old Trafford.
Robin van Persie missed a penalty on his return from injury as Manchester United lost its third successive Premier League game in a frustrating 1-0 defeat to West Brom.
A combination of Chris Brunt and Jonas Olsson struck the decisive blow shortly after the hour Saturday at Old Trafford, with the Albion skipper's 20-yard free kick taking a wicked deflection off his teammate to leave David de Gea helpless.
Van Persie had the chance to level in the 72nd minute when Saido Berahino was adjudged to have handled Antonio Valencia's cross inside the box, but the Dutchman - making his first start since mid-February - saw his spot kick saved by Boaz Myhill.
As was the case in their defeats at Chelsea and Everton over the last two weeks, Louis van Gaal's team could not make its domination of the ball count.
United was camped in West Brom's defensive third for much of the contest, but was simply unable to break Tony Pulis' stubborn men down, and Brunt's fortunate effort condemned the host to a third loss in a row for the first time since 2001.
Van Gaal's side remains in the box seat to secure fourth spot and a place in the UEFA Champions League, but its poor form has left the door ajar for Liverpool, which now sits four points behind United after beating QPR earlier in the day.
The pattern of the game was set from the off, with United dominating the ball and West Brom defending deep, just as it did to foil Liverpool last weekend.
Van Persie tested Myhill with a scuffed shot, and the returning striker could have opened the scoring in the 19th minute when he flashed a first-time effort narrowly wide from Ashley Young's low cross.
United continued to probe but, with Van Persie understandably rusty after his lengthy lay-off and Wayne Rooney playing in a more withdrawn role, it struggled to carve out clear-cut chances against a typically well-drilled Pulis side.
The second half began in much the same vein as the first, with Rooney having United's first attempt on goal with a 25-yard pot-shot that Myhill gathered easily.
But it was West Brom - victors at Old Trafford last season - who broke the deadlock completely against the run of play, when Olsson unwittingly deflected Brunt's free kick - which appeared to be going well wide - beyond De Gea.
United was gifted a golden opportunity to level shortly after, but Myhill made an excellent stop low to his left from Van Persie's penalty.
Thr goalkeeper was in outstanding form and was again on hand to deny Van Persie and substitute Angel di Maria in the closing stages, but West Brom stood firm as United continues to stagger toward Champions League qualification.