Aston Villa boss Steve Bruce said his team had been embarrassed in their 3-0 defeat to Cardiff.
Big-spending Villa remain one of the favourites to secure promotion back to the Premier League, but they were brushed aside in the Welsh capital as a brace from Nathaniel Mendez-Laing and a Junior Hoilett effort gave the Bluebirds a comfortable victory.
Former Rochdale winger Mendez-Laing, a Birmingham fan, formed an impressive Cardiff attack alongside striker Kenneth Zohore that Villa and John Terry simply could not deal with.
Victory moved Neil Warnock's side top of the Championship, but left Bruce downbeat.
He said: "Everything went wrong apart from the first 20 minutes. We made a bad mistake for the first goal and after that it was on the verge of embarrassing at times. It was a rude awakening for us.
"We didn't do the basics well and we looked fragile. Overall, it was a difficult afternoon.
"We have to do more. We are Aston Villa and we come with a big reputation. But away from home we have to be aware of what's coming.
"There were two decent chances at 0-0, but we didn't take them. It's one of the biggest defeats I've had in the Championship, we lost all our shape and balance."
After Scott Hogan had twice gone close for Villa, Mendez-Laing gave Cardiff the lead, heading home Hoilett's cross despite the close attentions of Terry and Neil Taylor.
Villa lacked a cutting edge up front and although they were not helped by losing Ahmed Elmohamady to a nasty mouth injury which may yet require surgery, Bruce's men did not look like scoring. In the second period, the visitors hit the bar through a deflected James Chester header.
But the chance simply saw Cardiff step up their game. The impressive Zohore danced down the right and his cross gave Hoilett a simple finish.
Mendez-Laing's curling effort made it 3-0 to complete the scoring and the final result could well have been even more convincing were it not for Villa goalkeeper Sam Johnstone.
Watching Bluebirds owner Vincent Tan confirmed he has no plans to sell the Welsh club to complete a dream day for Warnock.
The Cardiff boss said: "It's more or less the perfect result and Vincent couldn't have wished for a better game to come to. It's those sorts of games that are why I'm still in football.
"I was delighted with the goals we scored and everybody played their part in front of a good crowd.
"I have a good bunch of players here, they're honest and work hard for me. I wouldn't want to play against the likes of Zohore and I thought we saw vintage Hoilett today.
"But we've not done anything yet, we've won two games of football. Just wait until 10 games have gone, we've got all the top sides coming up. I don't get carried away. Sometimes you guys (the press) get carried away but if you do that, you get kicked in the teeth.
"The momentum is nice and it's good to get points in the early stages instead of playing catch-up, but every game is a difficult game. That's two out of the way and 44 to go.
"For me it's exciting what we have in attack, but we are still in the early stages and now we have to prepare for Sheffield United on Tuesday."