West Bromwich Albion moved up to third in the Championship as Jeremy Sarmiento's fabulous second-half strike proved the difference at Cardiff City.
Sarmiento came closest to scoring in a goalless first half with a shot that hit the post after a swift counter-attack from the visitors.
The Ecuadorian attacking midfielder, on loan from Brighton, then got the only goal of the game for the Baggies with a fine whipped effort which dipped and curled into the far corner.
Cardiff struggled to create many genuine chances as they searched for an equaliser and were limited to long-range shots from Josh Bowler and Rubin Colwill.
Albion's win closes the gap on Ipswich Town in the second automatic promotion spot to seven points, but Kieran McKenna's men have a chance to restore their advantage at home to Millwall on Wednesday.
As for Cardiff, defeat slips them to eighth in the table, three points adrift off the play-off places.
They had briefly climbed into the top six on Saturday with a dramatic late comeback win at Preston - but lasted only a couple of hours there after Albion won at The Hawthorns to end Ipswich's 12-match unbeaten run.
As disappointed as Erol Bulut and his players will be to lose, being in their current position still represents a huge improvement on the previous two seasons after Cardiff's successive battles against relegation.
For West Brom, meanwhile, six points from their two tricky matches suggests Carlos Corberan's side are in promising form as the promotion race intensifies with the looming festive fixture pile-up.
This game had the makings of an intriguing encounter as seventh met fifth in the Welsh capital but, despite starting at a lively pace, it lost some of its momentum when the visitors were dealt an early setback, losing captain Jed Wallace with what looked like a shoulder injury.
Albion still posed a threat and came close to taking the lead after half an hour when Grady Diangana led a rapid counter-attack from a Cardiff corner to find Sarmiento, whose shot rolled off the post.
Cardiff then had a chance of their own soon when Bowler weaved between opposition defenders before seeing his shot smothered by Alex Palmer.
From that point, neither side managed to create any clear-cut opportunities but, fortunately for Albion, Sarmiento only needed half an opening and it came in the 50th minute.
After darting down the left wing, he cut on to his right foot and, from an unfavourable angle, lashed a shot which arced over Cardiff goalkeeper Alex Runarsson and into the far corner.
The Baggies should have doubled their lead after 76 minutes but substitute Brandon Thomas-Asante headed over from close range.
Cardiff pressed for an equaliser but, other than speculative long-range efforts from Colwill, Bowler and Manolis Siopis, they did not really trouble Albion keeper Palmer.
Cardiff City: Runarsson, Romeo (Panzo 55’), McGuiness, Goutas, NG, Siopis, Ralls © (Wintle 55’), Robinson (Colwill 65’), Bowler, Tanner (Etete 75’), Méïté (Ugbo 55’). Subs not used: Alnwick, Adams, Sawyers, Rinomhota.
West Bromwich Albion: Palmer, Furlong, Kipré, Bartley, Townsend, Yokuşlu (Molumby 74’), Mowatt, Diangana (Fellows 65’), Swift (Maja 74’), Sarmiento (Phillips 65’), Wallace © (Thomas-Asante 21’). Subs not used: Griffiths, Ajayi, Pipa, Chalobah.