Rajiv van La Parra fired a stunning first-half winner as 10-man Huddersfield held on for another Premier League win to heap more pressure on West Brom boss Tony Pulis.
Van La Parra curled home the only goal just before half-time and although Christopher Schindler was sent off early in the second period, David Wagner's side produced more heroics to leave the visitors without a win in nine Premier League matches.
The Terriers, indebted to goalkeeper Jonas Lossl in stoppage time, beat Manchester United in their previous home game and this fourth league win of the season has lifted them five points clear of the Baggies, who have not won since mid-August.
Van La Parra fired Huddersfield's first effort over the crossbar as the home side set about breaking down West Brom's five-man defence.
As expected, the visitors sat deep and a formation which also comprised of three holding midfielders made it difficult for Huddersfield to work any openings.
West Brom threatened when Hal Robson-Kanu's clever pass set Jay Rodriguez free, but his shot was blocked by defender Schindler.
Visiting striker Rodriguez did well to head Aaron Mooy's excellent free-kick away for a corner and then the visitors had defender Kieran Gibbs to thank after his last-ditch tackle forced Tom Ince to blaze his shot off target.
Huddersfield had little to show after hogging possession and it was clear it needed something special against dogged opponents and Van La Parra delivered just before the interval.
Scott Malone turned the ball inside for Van La Parra 25 yards out near the left edge of the penalty area and the Dutchman curled a stunning shot beyond goalkeeper Ben Foster and inside the far post.
West Brom began the second half amid chants of 'we want Pulis out' from the visiting supporters and midfielder Gareth Barry was booked by referee Roger East for his foul on Town right-back Florent Hadergjonaj.
Town were dealt a blow in the 57th minute when Schindler was sent off. The German was shown his second yellow card for his foul on Ahmed Hegazi to leave his side a man down.
Pulis had already decided to send on all three of his substitutes, with Salomon Rondon, James McClean and Matt Phillips replacing Robson-Kanu, Grzegorz Krychowiak and Gareth McAuley respectively.
Wagner responded to Schindler's dismissal by sending on fellow central defender Martin Cranie for forward Elias Kachunga and midfielder Danny Williams for Van La Parra.
Wiiliams dropped into a five-man defence as Wagner looked to protect his side's lead and West Brom saw more of the ball.
Hogg blocked Jake Livermore's shot and Rondon headed skipper Jonny Evans' cross inches wide as the Terriers defended as if their lives depended on it.
Lossl rescued his side twice in stoppage time, first diving full length to keep out substitute McClean's late header and then producing another fine save to keep out Phillips' low shot.