Duffield was subbed out in the second quarter of the club’s 41-point defeat to the Cats at Simonds Stadium.
"It is only minor but he won't play this week," senior coach Ross Lyon told 6PR’s Sports Today on Monday night.
But Lyon said defender Lee Spurr, who was a late withdrawal from the game with severe gastro, would be right to resume.
There was more good news on the horizon for Freo, with the senior coach confirming stars Matthew Pavlich, Aaron Sandilands, David Mundy and Michael Barlow would return.
"Matthew, Aaron, Mundy and Barlow to this point have ticked off what they need to,” Lyon said.
“If they get through the two sessions they will certainly play."
Lyon also indicated three-time All Australian ruckman Sandilands could be used up forward because Freo has lacked a tall target in attack who could bring the ball to ground, where the club’s fleet of classy small forwards could capitalise.
"We think once Aaron gets into the team and you play him forward when you get held up at half-back, rather than have to switch, you can just kick the ball long to Aaron and get underneath him."
