Baggies boss Roy Hodgson was pleased to see his Albion side progress into the FA Cup fourth round – despite doing it the hard way.
Albion looked to be cruising into the next round of the cup after Peter Odemwingie and a Simon Cox header put the Baggies 2-0 just after the half hour mark.
But Cardiff fought back and goals from former Baggie Robert Earnshaw and Joe Mason drew the Bluebirds level.
Simon Cox then scored his second of the afternoon with a 25-yard thunderbolt in the 61st minute before completing his hat-trick in the final minute to cap an eye-catching performance and take home the match-ball.
"I'm pleased we won," said Hodgson.
"These matches are always going to be difficult.
"It's good that we didn't shoot ourselves in the foot by losing the game.
"We did surrender a two-goal lead, though.
"But it was good we were able to come back and win 4-2.”
Hodgson admitted afterwards that Cox took his opportunity to impress and has now played his way into the head coach’s plans for next weekend’s game against Norwich City.
"Cox was a clear positive from today," said the Baggies boss.
"We've had Shane Long and Peter Odemwingie up front for most of the season.
"They, I suppose, have been the obvious pairing that I think should be the ones who can take us onto greater things.
"As a result, Simon has had to be patient for his chance.
"He's been very patient and when the chance came today, he took it.
"I thought he did very well at Tottenham the other night as well.
"Adding the three goals today to his Tottenham performance is a clear positive for us as a football club and a great one for him.
"The way he played today, he clearly showed me he deserves a place in the team.
"We'll be thinking very seriously about that."
Should Simon Cox be selected against Norwich after his treble? Have your say here at Baggies Banter.