Displaying a fearless approach, the Belgian goalkeeper said Brendan Rodgers' side should not worry about their opposition regardless of who they play, as they simply need to do "what they do best."
Mignolet has only faced Manchester United once as a Liverpool player - a game the club won 1-0 thanks to a Daniel Sturridge winner at Anfield earlier this season.
And the 26-year-old is full of confidence going to Old Trafford for the reverse fixture, suggesting that any past meetings between the two sides before this season will count for nothing on Sunday.
"It's a big game but for me it's another game. Regardless of the opponent, we have to go out there and play as well as we can," he told Sky Sports News.
"We have had a good training week so far, working hard as a team, and we know what we have to do. We are going to do our best to get the job done.
"The past is the past and we have to do what we do best and not worry about the opposition.
"We need to worry about how Liverpool play the game and worry about the team ethic that we've got, worry about what we can do and not worry about the opposition. It's all about us."
Mignolet's confidence may have been further boosted by that fact that, unlike in recent seasons, both Robbie Fowler and Robbie Savage have recently insisted the Anfield side are going into the clash as favourites.
Man United's home form has seen them win just six games out of 13 in the Premier League this season, although Liverpool have done less damage on the road than on Merseyside, having won just six of 14.
However, the Reds have won their last four league games in a row, with two of them coming on the road. Most recently, they beat Southampton 3-0 at St Mary's.
United, by comparison, are also unbeaten in four league games, but have drawn two of them.
Is Mignolet right to be confident ahead of Liverpool's trip to Old Trafford?