First-half goals by Matheus Pereira and Grady Diangana, both from outside the area, gave the Baggies a commanding lead at the break.

The Bluebirds thought they had pulled one back through Robert Glatzel only for his header to be ruled offside, and things soon went from bad to worse for City as Charlie Austin raced clear to score the hosts' third.

Substitute Danny Ward scored twice as Cardiff threatened an unlikely late comeback, but Romaine Sawyers added a fourth for Albion in stoppage time to seal the win.

After seven games unbeaten in the Championship, Cardiff travelled to The Hawthorns to face a West Brom team fresh off their first defeat of the season.

But the Baggies had the best of the early exchanges and deserved their lead, Pereira curling a left-footed effort past Alex Smithies into the bottom corner.

As half-time loomed, Diangana tried his luck from the edge of the 18-yard box to double West Brom's lead before the break.

Cardiff looked much better after the interval, summer signing Glatzel looking the most likely to pull one back.

And the German striker thought he had done just that when his header from Marlon Pack's free-kick beat Sam Johnstone, but the flag was raised for offside.

Austin added to Cardiff's misery less than a minute later as his strike, again from outside the area, beat Smithies as the three points looked secured.

Undeterred though, Ward made an instant impact as he scored three minutes after coming on, slotting home Nathaniel Mendez-Laing's cross.

And with 86 minutes on the clock, Ward had his and Cardiff's second, the 27-year-old heading home Josh Murphy's cross.

As Cardiff threw men forward in search of a winner they left themselves exposed, and Pereira put Sawyers through to make sure the Baggies moved top of the table.

Cardiff City manager Neil Warnock:

It's difficult, we've had good opportunities and we feel let down by one or two decisions which have gone against us but that's typical when your luck is out.

"I said at half-time we need to put on a performance, we can't just feel sorry for ourselves, and we did. I thought in the second half we were a lot better.

"We've had loads of opportunities to get wins away from home, you can't concede four goals away from home and expect anything out of it so we need to look at it."

West Brom manager Slaven Bilic told BBC WM 95.6:

"A great game to watch- four goals and many chances. We are playing on the front foot; we are full of confidence.

"But we have to be more ruthless, more mature. We have to manage the game better. Credit to Cardiff, but we should have stopped their first goal, and with their first goal, it's game on.

"The (league) position could not be better. On the one hand, it's early days, but on the other hand, it's eleven games- it can't be a fluke! But we have to stay humble and learn from the mistakes."