The Blues travel to Old Trafford on Sunday knowing victory would send them top of the table just over two months after they languished 15 points behind United.
The also crashed out of the Champions League to Sir Alex Ferguson's men last month, a defeat which appeared to end their hopes of silverware this season and left Ancelotti all but resigned to losing his job.
Pointing the way: Carlo Ancelotti is targeting three points at Old Trafford on Sunday
However, the Italian - who has been crowned Barclays manager of the month for April - believes Sunday's match bears comparison to the biggest game in club football, saying: 'For us, it's like a final. We wanted to play the final of the Champions League, but we have to be happy to play this different kind of final. We can compare it to a final.
'We have to prepare for this game like it's a final. There is a lot of pressure around us to prepare for this game, but you have to have the skills to stay relaxed, maintain good control of your emotions, not be too afraid or worried, because that uses energy, and you need that during the game.'
Ancelotti felt confident enough to chastise those who had written his side off.
'You thought that this season was no good and now you have this opportunity,' he said. This season has not gone as everyone suggested. Everyone said that during the season.
Leading the way: Ancelotti parades the Barclays April manager of the month award
'This team is still alive. This means that these players have very good character, personality, are very professional. After the defeat against United, it was not easy to move on and turn. But they had a fantastic reaction.'
Chelsea won at Old Trafford last season, a victory which ultimately saw them lift the title. But Ancelotti was cautious about declaring three points this weekend, which would put them top on goal difference with two games remaining, would have the same effect.
He said: 'They are favourites as they have three points more. If we are able to win, nothing is decided. If they win, they will win the title.'
Indeed, Ancelotti warned that United - who this week reached the Champions League final - were a different prospect this season to last.
Battles: Chelsea lost out to Man United in their Champions League showdown
Ferguson's side were then without the injured Wayne Rooney, who has tormented Chelsea at times this term.
Ancelotti revealed he would not man mark the England striker, saying: 'His position is not so easy to control, he moves a lot, comes back and works for the team. But obviously we have to do something against him to control him. We never put one player against him. It'll be important to stay compact.'
The Italian's major tactical decision revolves around whether to play both Didier Drogba and Fernando Torres, with many claiming it would be a huge gamble to start with the latter.
'It's not a gamble - Torres is a fantastic striker,' said Ancelotti, who revealed he had yet to choose his strikeforce. He added: 'I want to say one thing: the line-up will not be what decides this game.
'This game will be decided through the courage of the players, the personality, the character. We don't need to be worried, afraid about this.'
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Explore more:People: Wayne Rooney, Alex Ferguson, Fernando Torres, Didier Drogba, Carlo Ancelotti Places: United Kingdom