Skipper Campbell insists Pompey should need no reminding of what lower-league opposition can do in a one-off clash after Harry Redknapp's team scraped through the two previous rounds against Ipswich and Plymouth.
But players like Sulley Muntari, John Utaka and Lucien Aubey are getting their first taste of the FA Cup and Campbell fears they might think it is an easy alternative to the Premier League.
Campbell says: "A lot of guys coming from playing abroad are used to having it easy in cup games against lower league teams.
"So it is up to us English players to put them right and make sure they know it's not that way here. Like Ipswich and Plymouth in the previous rounds, Preston will be chasing around trying to make life difficult for us.
"We've had to rely on David James making some great saves but we can't keep doing that and we've got to set our stall out right, match the opposition in the hard work department and then, hopefully, making our ability count.
"It is nice to have a cup run at this stage of the season when the team is doing well in the league. You never know where it might lead."