Jay Fulton scored his first goal for over a year just 60 seconds after coming on as a substitute to give Swansea 1-0 victory and pile more pressure on West Brom manager Ryan Mason.
Fulton - who had not scored since December 2024 - struck a superb shot from 25 yards in the 74th minute for the only goal of the game.
It proved enough to give Swansea their fourth successive home victory, but away-day troubles are piling up for Mason.
The Baggies boss has now seen his side lose nine matches in a row on the road, with this latest defeat dropping them to 17th in the table, seven points above the relegation zone.
With such a wretched recent away record, the pressure had been mounting on Mason and there was little in the opening half hour to ease his concerns.
Swansea dominated and although they were restricted to efforts from long range, Albion's inability to hold onto possession was notable.
They were almost made to pay early on when Swansea midfielder Marko Stamenic hit a rising shot that keeper Joe Wildsmith tipped over the bar.
Then, another turnover saw Swansea winger Ronald almost clear before he was chopped down by Callum Styles at the cost of a yellow card.
The visitors also picked up further first-half yellow cards for George Campbell, Alex Mowatt and Samuel Iling-Junior.
West Brom's only clear opportunity of the opening period came when Iling-Junior cut inside on the right flanks and forced Swansea keeper Lawrence Vigouroux into a sharp save at his near post.
As Swansea continued to press at the start of the second half, Ousmane Diakite became the fifth West Brom player to find himself cautioned when he scythed down Malick Yalcouye.
But despite having half of the opposition outfield players walking a disciplinary tightrope, Swansea were unable to force the issue for the opening goal as the match ticked past the hour mark, having sent on top scorer Zan Vipotnik from the bench.
The closest they came was when Ben Cabango headed onto the roof of the net from a corner.
That encouraged West Brom to launch a rare counter-attack and it needed another good save from Vigouroux to deny Karlan Grant.
The Baggies sensed there might be more reward in this game than a mere point and more intense pressure led to two chances for Mikey Johnston.
His shot was only half stopped by Vigouroux before Swansea scrambled to clear before Johnston went even closer with a header deflected around the post.
Suddenly, the match had ignited but it was Swansea who seized the initiative when Fulton put his team ahead in the 74th minute.
Ronald robbed Diakite 25 yards from goal, with the ball falling invitingly to Fulton, whose dipping shot flew past Wildsmith into the top left-hand corner.
It was Fulton's first goal for 13 months.
Vipotnik had a chance to seal things, but his shot was blocked.
The managers
Swansea's Vitor Matos:
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West Brom's Ryan Mason:
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