The Irish will secure a last-eight spot with a win in Pool D on Sunday, but O'Connell is anticipating a fierce battle against a side who must secure victory to keep their hopes of reaching the latter stages alive.
"I've no doubt we'll be battered up front and pushed to the limit," O'Connell is quoted as saying by ITV. "They're always incredibly physical games against Italy with the emphasis on the scrum, and big emphasis around their defence.
"There's no doubt it's going to be really tough, so that's what we've been preparing for."
Ireland have won both of their World Cup games to date and O'Connell is confident they can continue to impress in the tournament.
He added: "I can't remember a World Cup before where we've sat as a group on couches and watched all the games. That builds the excitement for us.
"Personally I'm more excited than ever because there aren't many more of them to come. I really enjoy the build-up."