The game of the day in Sky Bet League One on Saturday sees first play third, with Posh knowing victory would move them level on points with the O's.
Ferguson insists his players will thrive on the big-game atmosphere, with around 10,000 fans expected, and predicts that his side will bounce back from last weekend's disappointing defeat at struggling Colchester.
"These are the games that we normally play well in," said Ferguson at his pre-match press conference.
"We relish a big game in front of a big crowd and there's been a real sense of excitement at the club this week.
"Orient have been brilliant this season. They have an outstanding team and a top manager and they have a front four that will give us a real test.
"We have lost a couple of forwards, but I have Britt Assombalonga and Tyrone Barnett who have done well together this season and I have Nat Mendez-Laing and plenty of good midfielders.
"This is an important game, but we shouldn't place too much emphasis on the result as nothing will be decided this early in the season.
"It's a game we are keen to win though. Teams who go on to win titles don't usually lose two matches in a row and that's our challenge on Saturday."