Omer Riza says Cardiff City will face "big problems" if there is no reaction to their dismal display against Preston North End.

The Bluebirds are in the Championship relegation zone after Wednesday's 2-0 home loss to a Preston side who had not won in 10 matches before their trip to Wales.

In the club's first game since Riza was appointed manager on a deal until the end of the season, they produced arguably their worst display of what has been a difficult campaign.

Riza has pledged to make changes at Stoke City on Saturday after a performance he described as being "nowhere near the levels we need".

"I won't tolerate those sorts of performances from players, as a team or individuals. Things have got to change for the Stoke game," he said.

"If you don't do things properly, you get beaten. Before we talk about anything else, we have got to get that right again.

"There has to be a reaction. There is no other way. If there is not a reaction, then there are going to be big problems."

Riza was named interim Cardiff boss in September after the departure of Erol Bulut, who was sacked after taking only one point from the opening six games of the season.

Ex-Watford coach Riza made an impressive start to life at the helm, taking 14 points from his first seven fixtures, but Cardiff's form has since dipped alarmingly.

Riza was given a permanent contract last week – albeit one which only runs until next summer – despite a run of five games without a win.

Any hope that greater certainty over Cardiff's managerial situation would result in an upturn in fortunes on the pitch was dashed as they slumped to defeat by Preston.

"That's not my team," Riza added. "I don't like that sort of behaviour, I don't like it when we don't work, I don't like it when we don't fight, I don't like it when we haven't got desire, I don't like it when the opposition beat us like that – they beat us down.

"[It was] very flat from us. We didn't play at the weekend. We trained Sunday, Monday, Tuesday, so it's not like they had days off.

"We applied what we needed to do but the boys, they have got to look at themselves and I don't usually say that."

Some Cardiff fans chanted "Riza, sort it out" during the Preston defeat, their third straight home loss, while there were boos at full-time.

"It was disappointing to hear the boos, disappointing to hear the frustrations and I join them in that as well," Riza added.

"Sometimes it's not tactics, it's not systems, it's desire, it's quality. That's what we are going to be looking for – energy to want to play, intensity to want to play."