City top the Premier League with a superior goal difference with just two games remaining and have the chance to claim their first top-flight championship in 44 years if they can match United’s results over the final two games.
City's next game is at Newcastle on Sunday, whilst United host Swansea on the same day and Mancini believes their concluding fixtures to the campaign make the Old Trafford side favourites for the title.
"It is not finished," Mancini told reporters. "If we think it is finished, we will be making a big mistake.
"United are the favourites. They have easy games. They play against Swansea and Sunderland.
"We have two strong games, Newcastle and QPR. One plays for the Champions League, the other for relegation.
"It is important that we are on the top now but it is more important to be there after May 13."
|1/2||Manchester City are 1/2 with William Hill to win the Premier League this season.|
Sir Alex Ferguson seemed to set his side out in a defensive formation, in the knowledge that a point would keep them in pole position for a 20th league title and Mancini believes that United would have settled for a share of the spoils.
"It was important for them to play for a draw because the championship would have been finished," he said.
"We played better. We deserved to win but it was difficult because they had all the players behind the ball."
In four games, City have managed to claw back an eight-point deficit and Mancini admits the situation is bizarre.
"Football is crazy," he said.
"It is important to always believe in yourself when you have a bad moment. We were on the top for 28 games and I think we deserve another chance.
"But in two games, anything can happen.
"It is enough for my players that they remember six weeks ago and we were four points ahead of United. In two games we lost everything. Up to now, we have done nothing."
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