That's because City's boss believes his side will only secure a top-four Premier League finish if they "want it 200 per cent".
And Mancini wants to see his men shake off the tag of inconsistency which has been attached to the club for as long as anyone can remember.
The Blues go to Sunderland fresh and full of confidence, having had a two-week gap since their 4-2 victory at Chelsea.
Mancini feels that magnificent win at Stamford Bridge was a clear signal that City are good enough to beat anyone.
And so in theory, victory over a Black Cats side who had gone four months without a win before thrashing Bolton 4-0 on Tuesday night should be no problem.
But Mancini knows that football doesn't always work like that - especially not in City's case.
Mancini said: "I think that we have a good chance at this moment, because we have one game in hand on Tottenham and two games in hand on Liverpool.
"For this, it depends on us. We have to want it 200 per cent. We must go into every game focused.
"We have to be focused for Sunderland, and than after that game, we must be focused on Fulham.
"I am very happy, because in the last month, I feel we have played like a team. This is important for me and the players - because if you don't play like that, then you don't beat a team such as Chelsea."
Sunderland danger
Those who watch Sunderland on a regular basis felt that a victory was on the cards long before they ended their 14-match winless Premier League streak by thumping Bolton in midweek.
Mancini said: "In the last two games, Sunderland have played very well. They beat Bolton 4-0 and they drew against Fulham.
"After Chelsea, we would have been happy to have another game quickly, but it wasn't possible.
"It's important that now we put the game against Chelsea in the past.
"Now we have to focus our concentration on Sunderland.
"I think the players will have benefited from the rest they have had. I'm happy, because we have worked very well this week after four days of rest.
"I think we can do a good job on Sunday."
Meanwhile, Kolo Toure has a big role to play in City's bid to crack the top four - despite enduring a tricky first season at Eastlands.
Toure hasn't always looked convincing in central defence following his £14million move from Arsenal last summer.
His recent absence because of a knee problem has allowed Vincent Kompany to form a partnership with Joleon Lescott in the middle of the back line - and give Mancini a selection dilemma.
Mancini said: "Vincent Kompany and Joleon Lescott have been playing together because Kolo had a problem for two weeks and couldn't play for his national team.
"Now Kolo is good again. He's fit again.
"We have Sunderland, Fulham, Everton, and Wigan coming up. We have many games. I need all the players at 100 per cent."
What do you think? Have your say.
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Nonna Mancini, In My Bungalow (13/03/2010 at 07:43)
If not, we're screwed.
Every Premiership team has known since early on in the season Toure's weaknesses, and goes for our jugular.
"We have Sunderland, Fulham, Everton, and Wigan coming up" - does anyone seriously think these teams will sit back and let us have an easy time of it in central defence?
Also, this Myth that City are unpredictable, inconsistent, blah blah blah, is nonsense - look at similar teams around us in the last 30 years, their results are comparable. Lack of success is down to lack of consistency of management and board, poor financial backing compared to the "big four", sheer bad luck due to missing out on Champion's league revenue in the early years of the Premiership etc...
We are no better or worse than Spuds, Villa, Everton etc.. when it comes to cock-ups and bad luck/ judgement, and now we have the opportunity to put this alleged hoodoo to bed - we've consistently hammered the rags since King Kev gave us back our belief, Arsenal and Chelsea have been put to the sword this season, next we've got the silverware and Champion's league to deal with - which we will now the backing and vision is in place.