The champions ended January trailing rivals Manchester United by seven points but Mancini is hopeful of wiping out the deficit in the coming weeks.
City dropped two points as they were held to a goalless draw at QPR in midweek but Mancini thinks the gap can be closed during a month when United resume their Champions League campaign.
Mancini said: "This doesn't change (anything).
"I think when we arrive at the end of February, the gap will be very, very small.
"In every championship, never one team won a title in January. We should fight until April.
"If they have seven, eight, nine points (lead) in April, it could be difficult, maybe. But in this moment we have a big chance.
"Every team during the season has two or three weeks when they don't play well, when their performances go down and they don't score.
"Even if you have fantastic strikers, like the situation we had last year, there were some moments when we scored three or four goals a game but then didn't score for three or four games and we didn't know why.
"It could be the same for them (United) now."
City face Liverpool, Southampton and Chelsea during February as well as hosting Championship side Leeds in the FA Cup.
United have three league fixtures, against Fulham, Everton and QPR, and an FA Cup tie, versus Reading, but also face Real Madrid in an eagerly-anticipated Champions League encounter.
They tackle the Spanish giants again in the second leg of their tie in early March and Mancini believes this could be the time for his side to strike.
The Italian said: "Yes, it could be. They are two important games for United so I think that February and March could be the time when it's possible to decide this championship."
City face a Liverpool side this weekend boasting one of the most in-form strikers in the Premier League in Luis Suarez.
Mancini was linked with a £40million swoop for the Uruguayan, who has scored 22 goals this term, earlier in the season but he is not willing to get drawn on that subject.
When asked about Suarez at his pre-match press conference, Mancini said: "Suarez? He plays for Liverpool. He has quality and is strong."
City will also have to try to keep Suarez quiet without defensive linchpin and captain Vincent Kompany.
The Belgium international suffered another calf strain in last week's FA Cup fourth-round win at Stoke last weekend and could be out until after the fifth round against Leeds in a fortnight.
City have admitted concern over the recurring nature of Kompany's problem but he is not expected to need an operation.
Mancini said: "He has this problem. An injury to the calf is a bad injury.
"You can have this for a long time. Vinny needs to work and have treatment but I'm not worried about an operation.
"He did this problem in March last year after five minutes against Sporting Lisbon. We need to manage him well."
Liverpool's recent run of good form was undermined by a shock FA Cup loss at League One Oldham last weekend.
But they responded with a positive display in a 2-2 draw at Arsenal in midweek, a game attended by Mancini, and the City boss reckons Brendan Rodgers is doing a good job at Anfield.
Mancini spoke to Rodgers soon after he took over at City with a view to appointing him as his assistant but the Northern Irishman went on to take charge at Swansea and moved to Liverpool last summer.
Mancini said: "Three years ago before David (Platt), I talked with him but for me it was easier to take David because I played with him, I knew him very well and David spoke Italian.
"But I was impressed with Brendan, I met him in Milan.
"I spoke about him with our chief scout and also with (then chief executive) Garry Cook.
"He impressed me because he knows his football very well. He showed he is a good manager in the last two years.
"I'm not surprised he went to Liverpool because he's a good manager."