A 66th-minute Nathan Ellington goal saw West Brom to a valuable win over promotion rivals Cardiff.
Ellington has not started for the Baggies in over three months
Robert Koren proved an early threat to the visitors, though Steve Thompson and debutant Darcy Byrne had chances for the Bluebirds in a goalless first 45.
Kevin Philips had a goal ruled out for offside, but it needed Ellington's introduction to break the deadlock.
Six minutes after coming on the striker speared a spectacular 25-yard effort from the left into the far top corner.
The win was the Baggies' ninth in 10 home games and ended Cardiff's five-match unbeaten run.
The visitors have also been stung by a suspected broken toe suffered by striker Jason Byrne.
West Brom manager Tony Mowbray:
"We got the three points on the back of what was an untypical performance from us.
"We were defensively very poor in the first half, slack, and we gave Cardiff too many chances.
"In the second half there was a huge improvement defensively and Nathan came off the bench to score a very good goal.
"But, overall, I have to say we have played much better than that and not got anything out of previous games this season so I suppose I have to be happy with the three points."
Cardiff manager Dave Jones:
"I think a draw would have been the fair result. Both goalkeepers were busy - theirs busier than ours - but we made a mistake giving the ball away in the middle of the park and got punished by a Nathan Ellington wonder goal.
"A lot of people had us down for a beating at West Brom because I had so many of my big hitters missing.
"But, as it turned out, we created the game's better chances, especially in the first half when our movement caused West Brom all sorts of problems.
"Even when West Brom scored we still had chances to get an equaliser, but it was not to be.
"I am very proud of my players and the performance they gave because they frightened West Brom to death and showed there is a very bright future at this football club.
"But we want the future now, we are greedy and we want promotion now so we are going for it."
West Brom: Kiely, Albrechtsen, Clement, McShane, Robinson, Greening, Chaplow (Hartson 61), Koumas (Carter 71), Koren, Kamara, Phillips (Ellington 60).
Subs Not Used: Daniels, Gera.
Goals: Ellington 66.
Cardiff: Alexander, Gunter, Johnson, McNaughton, Ledley, Parry (Flood 80), McPhail, Blake, Whittingham, Byrne (Redan 71), Thompson (Campbell 86).
Subs Not Used: Forde, Gilbert.
Ref: G Laws (Tyne & Wear).