City take on Chelsea at home on Wednesday night and they know that they must win the game to stay a point behind the champions.
But should City slip up again then an in-form United side would surely be favourites to win the title for a 20th time.
But Mancini said: “We will win the title, we will win.
“We will do everything to win the title. We need to think positive, always.
“Until now we have had a fantastic Premier League, we need to continue like this.
“It is better to stay on the top – always – but I said a month ago it could be that we will go into the second position. This can happen.
“We had difficult fixtures, different from United, but it has not changed. We have everything in our hands. There is one game difference – potentially we are one point behind.”