The Black Cats edged out United in the Capital One Cup semi-final last season before recording a 1-0 win at Old Trafford in April, and Mannone believes that a similar result would hand Gus Poyet's side a big boost heading into their next few matches.
"Confidence is everything in football and we have already proved we can beat them," the Italian told reporters. "They are still one of the best clubs in the country, so to win again would give us a boost for the next six to eight games.
"We need to take points early on and not make the same mistakes as last year."
Sunderland started their Premier League campaign by earning a 2-2 draw against West Bromwich Albion last Saturday.