The Foxes chief admits Louis van Gaal's side are starting to click after they kick-started their season last week.
A 4-0 Premier League win over QPR was their first victory of the season under Van Gaal after a troubled start which saw them lose to Swansea and suffer a 4-0 humiliation at MK Dons in the Capital One Cup.
But Pearson insisted United have begun their road to recovery ahead of their clash at the King Power Stadium on Sunday.
He said: "United look like they have a swagger back, they have added quality
Whenever there is a change in manager you can have people who have a short-term impact.
"When you have someone in charge for as long as Sir Alex (Ferguson) the transition period will never be easy.
"They have been a huge presence within the English game for a long time
I'm sure they will reignite that at some point."
Leicester have impressed on their return to the Premier League after a decade away, drawing at home to Everton and Arsenal before their opening win at Stoke last week.
They still earned plaudits in a narrow defeat at Chelsea and Pearson wants his side to maintain their momentum on Sunday.
He said: "If you look at the Arsenal game, there is no doubt there was a spirit and togetherness
We have some very exciting players and prospects.
"We can't be happy with what we've done so far
I don't know what system they (United) will play to start with.
"It will be interesting in itself
They have some very good players, there is no doubt about that
Can we play the game not the occasion?
"The scrutiny and build up to games like this would suggest there is an awful lot at stake
That in itself can bring different pressures.
"We have to get our preparation right and try and not get too wrapped up in the occasion."
Source : PA
Source: PA