Fry recalled that the Posh suffered a 5-0 defeat in the same fixture in 2001, and he is expecting an even more difficult game on Sunday.
"It might be different this time," he told the Daily Mail.
"They only had Zola, Dennis Wise, Jimmy Floyd Hasselbaink, Marcel Desailly, John Terry. They weren't as good back then.
"Christ knows what score it'll be, but I'm pleased for my chairman Darragh MacAnthony. He's been here 10 years and put in £18million to keep the club going.
"I'm pleased for our young manager Grant McCann — our Special One. And the players because the FA Cup gives them an opportunity to shine and make people take notice.
"It's fantastic for the fans. We had 6,000 tickets and they went within a day and a half. We can't get 6,000 at home but they went."