After a dull first half mainly controlled by the hosts, the match sprung to life after the break when Rajiv van La Parra and Steve Mounié struck within eight minutes of each other to give the Terriers the advantage.
Baggies defender Craig Dawson headed Alan Pardew's side back into the game just past the hour-mark, but that goal eventually turned out to be a consolation in a loss which could be the final nail in the coffin.
Hadergjonaj steals the headlines
Jonas Lössl – 7:
Made a few important saves, most notably stopping Chris Brunt equalise from a late free-kick, but looked nervous when collecting crosses and was made to pay for West Brom's goal.
Florent Hadergjonaj – 9 (MOTM):
Best performance since joining Huddersfield as he constantly marauded up and down the flank to clip in good crosses and was unlucky to be substituted for Tommy Smith so early in the second half.
Christopher Schindler – 8:
Another solid defensive showing alongside 'Zanka' where he dealt with the physical threat of Solomon Rondón admirably and kept his cool when the visitors were under relentless pressure in the latter stages.
Mathias Jørgensen – 8:
His partnership with Schindler continued to grow stronger at the Hawthorns as they both limited the danger of Jay Rodriguez and Rondón; unfairly left out of defensive praise at times this season.
Terrence Kongolo – 7:
The young Frenchman impressed again on Saturday, he's fitted in brilliantly since his January loan from AS Monaco and it was a delight to see how well he covered van La Parra when possession was lost.
A midfield display Mooy would be proud of
Jonathan Hogg – 7:
You can see the passion he has for the club every time he puts on the shirt and another battling showing was required today against tough midfield opposition.
Danny Williams – 8:
Was unlucky not to score on two occasions, one which forced a tremendous save out of Ben Foster, but his midfield performance was good and Hogg's presence helps express his attacking-self a bit more.
van La Parra inflicts more West Brom misery
Collin Quaner – 7:
Became the Terriers' top assister this term (4) with his unselfish lay-off for van La Parra's opener after terrific work to enter the box and was the away side's brightest spark in a backs-against-the-wall first half.
Alex Pritchard – 8:
Provided the creative quality from no. 10 needed if Town are to stay up this season and how he slotted Mounié in was top class - brought off for Depoitre after winning none of four aerial duels though.
Rajiv van La Parra – 8:
Scored against the Baggies again, albeit in rather scruffy fashion in comparison to his worldie at the John Smith's Stadium, and made more tackles than any other player on the pitch (6) by pressing high up.
Steve Mounié – 8:
Produced an exquisite finish while making it look easy to seal a huge three points and put in a terrific shift all match to close down the opposition early as the spearhead of an impressive attack on the day.
Tommy Smith (Florent Hadergjonaj, min. 53) - 7:
Brought on for Hadergjonaj because he's the more defensive-minded of the two and the switch seemed to work.
Laurent Depotire (Alex Pritchard, min. 77) – 7:
Brought on to win aerial duels high up the pitch and he did exactly that which helped hang onto the three points.
Tom Ince (Rajiv van La Parra, min. 89) – N/A:
A late introduction.