Third-placed United have taken 22 points from a possible 24 in the Premier League and head to White Hart Lane on the back of a convincing 3-1 victory over Newcastle United on Friday.
However, Tottenham are also in high spirits following three league wins in succession and Pochettino believes his side should approach the visit of Louis van Gaal's men with confidence.
"We need this mentality to go into this game, to be brave, to try to fight in every action and try to play better than them," Pochettino told Tottenham's official website.
"Manchester United are in a very good moment like us and we have a tough game ahead. We need to be clever and first to rest after a big effort at Leicester [where Tottenham won 2-1 on Friday].
"It will be a great atmosphere, a day for all the families to enjoy and in front of us, another very good team, but we will try to get the three points.
"We have showed character in every game and it’s important to keep this feeling."
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