Both clubs still have a chance of winning a play-off place.
The Foxes must win a league game at the City Ground for the first time since 1972 and hope Bolton do not beat Blackpool.
Forest must better Bolton's result, although victory for Billy Davies' side combined with Crystal Palace losing to Peterborough would also seal a top-six spot irrespective of what the Trotters do.
With so much potentially riding on Saturday's game, Pearson does not expect it feel like a league fixture.
"It will be very much like a cup tie I would imagine," said the Leicester boss. "There is a lot riding on it and it is also a local derby. We will be taking a lot of fans there so I think we can expect a terrific atmosphere as well.
"But as with all local derbies it is about getting the performance right and doing all we can to win it. It is a huge game for the club and we have just got to try and make sure the performance is such that it gives us a good chance of winning the game.
"That is the most important thing first and foremost, winning the game. It has all come down to the last game of the season and unfortunately for us it is not in our own hands in that even if we win we are not guaranteed to get into the play offs.
"So we are going to need a bit of fortune but, as I said, first and foremost we have got to get our own game right and we will all be raring to go and get the win."