Huddersfield Town took a huge step towards Premier League survival with a gutsy victory over West Bromwich Albion at The Hawthorns.
The Terriers were by far the better side over the course of the clash and were handed a two-goal lead by Rajiv van la Parra and Steve Mounie in the second half.
Craig Dawson halved the deficit for the hosts, but Town held on to record arguably their most important win of the season so far.
Head coach David Wagner made two changes to the side that took on Manchester United in the FA Cup last week, with Jonathan Hogg and Alex Pritchard coming in for the ill Philip Billing and Tom Ince.
With so much at stake, both sides were intent on keeping themselves in the clash in the first period, leading to a dull opening half hour.
Salomon Rondon fired a warning shot over the bar early on, but neither team had a clear sight of goal until the 36 minute, when Collin Quaner released Florent Hadergjonaj down the right wing.
The Switzerland international got past Kieran Gibbs and to the byline before cutting back for the onrushing Alex Pritchard.
The creative midfielder – who Town brought in from Norwich City in the January transfer window – steered his effort on target, but was denied by the head of teammates Steve Mounie, who couldn't contort his body out of the way of the goal-bound effort.
The ball dropped to van la Parra on the left of the box, but the Dutchman – who netted in the reverse fixture in November – saw his strike turned wide of the post by a Baggies defender.
The best chance of the half however fell to the hosts.
Shortly before half time, a misplaced pass on the left allowed Ahmed Hegazi to step on to the ball and slide Phillips in down the right wing.
The Scotland international clipped a lofted cross into the box and on to James McClean's left boot, but the Irishman couldn't keep his volley down, leading to cries of anguish from the Premier League's bottom club's fans.
The supporters booed off their side at half time, with the stop-start, broken display not appeasing the home fans.
And Town heaped more misery on to the home side just two minutes into the second half.
A long ball allowed Mounie to get in behind the Baggies, with the Benin international finding Quaner on the right side of the box.
The former Union Berlin man dragged the ball across the area and into the path of van la Parra, whose scuffed right-footed effort was hit just well enough to beat Ben Foster and nestle in the bottom corner of the net.
After the opening goal, West Brom began to fall apart, with Town in the ascendancy for the majority of the second period.
Williams was next to worry Foster, with his drilled effort fizzing just wide of the former Manchester United gloveman's far post.
Minutes later, the keeper did have a touch of the ball – but only to pull it out of his net for a second time.
Mounie was the man to punish the hosts for the second time after a beautiful reverse pass from Pritchard slipped him in one on one with the keeper.
The in-form Mounie made no mistake and bent the ball past Foster to record his fifth goal in his last six appearances.
“The Town are staying up” filled the air after Town's second, but the ecstasy was short-lived.
West Brom earned a corner a piled men into the box, pinning Jonas Lossl on his line.
Craig Dawson met Chris Brunt's delivery with a well-timed header to haul the hosts back into the clash.
The goal gave Alan Pardew's side confidence and the Baggies – who had been dreadful for 65 minutes – worked their way back into the match.
Lossl was called upon to make a good save from Brunt's free kick, while Foster was also tested by a sweet volley from the boot of Williams.
The hosts pushed forward and continued to look dangerous from set-pieces, with Dawson heading inches over the bar following another Brunt corner.
But Town held on to record their first ever Premier League double and stretch the gap between the two sides to 10 points.
The win also lifted Town to 14th in the top flight, three points clear of Swansea City in 18th.