The Welsh outfit - now managerless following the sacking on Friday of their boss Malky Mackay - are currently 16th, just a point clear of the relegation zone.
But with rock-bottom Sunderland having beaten some of the division's high-fliers this term and dropped points against sides closer to them in the table, Mannone believes it would be beneficial for the Wearsiders to go about their task in the 5.30pm kick-off with the mindset that their hosts are in a far better position than they really are.
The Italian said: "Cardiff is another tough game and we have to take it as if they are in the top four.
"Cardiff are fighting with us and we need to believe.
"We may be bottom but if you don't believe then you can't fight."
Sunderland, three points adrift of safety at present, should go into the Cardiff encounter full of confidence off the back of their surprise 1-0 triumph at fifth-placed Everton on Boxing Day - only their third league win this term.
It was their maiden away victory of the season, and brought to an end a winless run that had been standing at six top-flight matches.
It was also the first time since 1996 that Sunderland had won at Everton, who, prior to this week's contest, had not lost a home league match in the whole of 2013.
And with regard to achieving the unexpected, certainly Mannone is not buying into the idea that being bottom of the table at Christmas is as good as a guarantee that a team will be relegated by the end of the campaign.
"I don't believe in that. It may happen many times, but a lot can happen," he said.
"No team had won at Everton for a year and we hadn't since 1996 but we managed to get the win.
"Things can change and we must believe.
"We've got a tough second part of the season and still have a lot of teams to play around us.
"We need to believe, because when you do you can make crazy things happen."
While representing a milestone for Sunderland in several ways, the game at Goodison Park was also a stand-out one on a personal level for Mannone.
Keeping a clean sheet for the third successive league fixture, the 25-year-old put in a particularly eye-catching display, producing a string of impressive saves in the second half to help keep 10-man Everton at bay.
Mannone joined Sunderland over the summer from Arsenal, who he had been with for several years but made very few first-team appearances for and been loaned to Barnsley and Hull by.
Since coming on as a substitute to replace the injured Keiren Westwood in a league match against Hull in November, Mannone has played in all of the 10 games that have followed for the Black Cats in all competitions.
And reflecting on the chance that has been given to him by Gus Poyet, who took over as Sunderland boss in October, Mannone said: "I'm really happy now because I've got the chance to play and that's all I've been searching for for years.
"I never had a manager who believes in me like Mr Poyet.
"Finally I've got a good manager who understands me, and I want to push on."
Sunderland will again be without Wes Brown for Saturday's match, while it remains to be seen whether or not his fellow defender John O'Shea is able to feature.
The pair missed the Everton win, with Brown starting a three-match suspension and O'Shea nursing a shoulder problem.
Definitely still ruled out through injury are goalkeeper Westwood (shoulder) and yet another defender, Carlos Cuellar (hip).