John Swift made it 3-0 in the 83rd minute and Reading also squandered a late penalty as Yakou Meite's spot-kick was saved by Alex Smithies.

"We've been poor at the back, really poor," Warnock said.

"It was the same at Wigan (where Cardiff lost 3-2) when we should have won that game.

"You can't really cater for the goals that we've let in. I don't think it's been an individual really. Quite a few of them have been making mistakes and we've been punished for them.

"You've got to defend better than we did today. We're in the Championship and some of our defending was really poor.

"When you're defending as badly as we are, it doesn't matter whether you're playing in the under-13s or in the Premier League, you're going to lose games.

"It's funny, I felt so comfortable in that first 20 minutes. Probably too much really.

"But then we go and concede a goal from our own free-kick. That is such bad defending, I still can't believe it.

"That gave Reading a lift. And then there was more bad defending for their second goal.

"But even at half-time, I thought that if we got the third goal then we could get something from the game.

"But once their third goal went in, it was over then. It was the end of the game."

Reading collected their first points of the season and manager Jose Gomes said: "Like all the Reading fans, I am very happy.

"My players worked very well and really followed our plan. We knew the way in which Cardiff played and my players really respected everything that they should.

"They did it and they got the results for this organisation, teamwork and good defensive play.

"We also created some very good combinations in attack and nice situations from which we could score even more goals."

Gomes praised two-goal striker Puscas.

"It was good for him," Gomes said. "It's always good for the strikers.

"It gives them confidence every time that they score. But we cannot forget that if they receive so many good balls, it means that other players played well enough to give them these balls.

"Like I said, it was good teamwork. But we are still in the beginning of the season and, for sure, there will be a lot of ups and downs – like all the teams in the world."