The Bluebirds are only a point behind resurgent Derby County, but have also seen Plymouth and Luton below them move to within two points of their tally as they look anxiously towards third tier football for the first time since 2003.
Riza says he has to remain confident that the Bluebirds can pull off a late escape.
“Sheffield United have lost their last three games and need to win to get back into the promotion spots, we need to go there and try to win and it’s going to be a tough, tough mountain,” he said.
“But there is still an opportunity, still a chance and still belief.
“I have to be confident. If you have no belief you have nothing. But we have to match it with performance and points. We haven’t managed to do that, but we still have four games and it is not over yet.”
However, following a crushing defeat to Stoke, Riza admits he does not know if Cardiff’s board will allow him to see the season through, having only taken over in September following the sacking of previous boss, Erol Bulut.
When asked if he expected to carry on, Riza replied: “I don’t know, you’ve got to ask the board, it’s not my place to answer that question.
“All I know is I am doing everything I can as a manager to try and get the results we need to avoid relegation and stay up.
“That’s all I can do. That’s what I will continue to do, right until the end, or while I am given the opportunity to do it. If not, if it doesn’t go that way, then I have to accept it.”
Cardiff’s defeat saw them booed off by their own supporters, but Riza says he understands the reaction after Will Fish’s late own goal consigned them to a particularly damaging defeat against a relegation rival.
“We’ve lost to a basic moment that we needed to deal with,” Riza added.
“I’d expect the reaction from the fans. At 0-0 they were behind us. When we concede as late as we did, it deflates the fans and they made their frustrations clear.
“It is difficult when it happens, but it’s the nature of the beast with football. We are trying to approach things as positively as we can.”
BBC News