Sir Alex Ferguson is banking on "the best home record in Europe" to shove Manchester United over the Premier League title finishing line.
While his opposite number at Chelsea, Carlo Ancelotti, said his side were treating the game like a "final", the United manager is confident an excellent record at Old Trafford that has seen them pick up 49 of an available 51 points will see them avoid defeat.
"Our home record is probably the best in Europe," Ferguson said. "It is the reason we are there. Some of the performances at home this season have been absolutely terrific.
"Hopefully, it will get us the result we want on Sunday, because this is a big game. If we win, we should win the league."
Although United cannot clinch a record 19th championship this weekend, the game will have far-reaching consequences on the destination of the title.
If Chelsea win they will go to the top on goal difference with two games remaining.
If United win they will be six points clear and needing a single point from fixtures against relegation candidates Blackburn and Blackpool to win the title.
Even a draw would not be a bad result for United, as it would leave them just four points off their target and with their fate still in their own hands.
Chelsea's impressive recent form - 25 points from the last 27 - plus victories in their past three league meetings with United, ensure they cannot be taken lightly.
Ferguson's faith is reinforced by back-to-back wins in the Champions League quarter-final over Chelsea.
But last weekend's defeat at Arsenal has given the defending champions fresh hope.
"Us losing to Arsenal has opened the door for them," Ferguson said of Chelsea. "But we always said it is a very difficult league.
"The Premier League is hard to win. We know because we have been involved in the championship races for 19 years."
The sight of his team struggling at the Emirates Stadium confirmed in Ferguson's mind that changes had to be made for Wednesday's Champions League semi-final with Schalke.
Part one of the plan worked to perfection as United's second-string side eased through to a Champions League final meeting with Barcelona at Wembley Stadium on May 28.
Now he can only hope the concluding effort is just as effective.
"Everyone is aware of the magnitude of Sunday's game," Ferguson said. "It is one of the reasons why I picked the team I did on Wednesday. I wanted to give us a real chance. We will have a fresh team, and that makes a difference at this time of the season."
For Chelsea, at one stage being 15 points adrift of United, the chance to retain the title is a bonus and Ancelotti said his players needed to embrace that mind set.
"This team is still alive," the Italian coach said. "This means that these players have very good character, personality, are very professional. After the defeat against United [in the Champions League], it was not easy to move on and turn. But they had a fantastic reaction.
"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."
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, would have the same effect this time.
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."
