With their most important defender Michael Jamison still on the sidelines, the Blues will have their work cut out trying to quell the big man's influence.
"He's been in great form. I suppose that's a concern for us," Ratten said during his weekly media conference.
"If Petrie dominates we'll be under enormous pressure. How we stop him? Maybe the supply. They're getting a lot of footy inside 50 so that's allowing Petrie to get to more contests."
Lachlan Henderson has been a big improver as a defender in the past month, but Carlton has had its struggles with the opposition’s most dangerous forwards.
Michael Hurley, Barry Hall and Travis Cloke have all been significant in recent battles, while Petrie's form (24 marks and eight goals in the last two games) suggests he'll be another massive challenge.
"I think the success of the Kangaroos has been when they're marking the ball inside 50, that's been the biggest scoring source they've had when they're winning games."
"It'll be something that we really analyse at match committee a lot deeper, how we control him and the ball supply."
Petrie won't be the only challenge for the Blues’ defenders though with Aaron Edwards, Ben Warren and even swing-man Cameron Pedersen providing dangerous targets.
Edwards pulled down eight marks against the Lions working further up the ground, while Pedersen has proven a handy addition at both ends of the ground with goals in five of his last six matches.
