The Scottish international says the Anfield aces will not come to Old Trafford with the same safety-first attitude which Rangers used to such smothering effect in the Champions League earlier this week.
The battles between the north-west giants are always highlights in the Barclays Premier League fixture calendar no matter what their respective positions in the league.
That Liverpool have now gone 20 years without a title and are trying to rebuild under Roy Hodgson has not lessened United's desire for victory, a need made all the more acute because of disappointing away draws at Fulham and Everton.
Paul Scholes is virtually certain to return, which should at least provide the Red Devils midfield with some of the inventiveness it was so badly lacking in Tuesday night's 0-0 draw.
And Fletcher feels United can also profit from the more expansive approach he expects Liverpool to adopt.
"Liverpool's history will not allow them to put nine men behind the ball," he said, reflecting on how Rangers were so successful in stifling United this week.
"That is not their style. Under Roy Hodgson I am sure they will be disciplined and well drilled. But they will look to win the match as well."
In making 10 changes to his starting line-up in midweek, Ferguson seemed to be emphasising the importance of Sunday's match.
GREAT HISTORY
He quickly learned the importance of beating Liverpool at the start of his staggering 24-year reign at Old Trafford.
And while United's success has left their fellow north-west giants in the shade over the past two decades, they remain a foe to be beaten with relish.
"It is the biggest game because of the history and the success the two clubs have had," reflected Fletcher.
"We have had a lot of battles over the years. There is a great history between the two clubs and we have equalled their number of league titles now, so a lot is looked into that.
"It is a massive occasion, when form goes out of the window.
"Liverpool will be looking to kick-start their season but to have them at Old Trafford so early just emphasises the importance of getting the right result."
United's strike force has plundered 11 goals in its opening four Barclays Premier League fixtures.
Problems have been evident at the back though, where Ferguson's side have conceded late goals - and dropped points - in both their away matches.
It is a problem that Fletcher recognises must be stopped.
"There has been nothing wrong with our overall performances," said the Scotland skipper.
"We are playing some good stuff at times. What we are missing just now is the killer instinct. We need to change that as soon as possible."
