Port Adelaide say Karl Amon will miss up to a month with a fractured patella.
The club's head of high performance Darren Burgess said while Amon sustained a knock to the knee against the Cats, it wasn’t thought the injury was as bad as scans have subsequently revealed.
“We felt it was a minor knock originally, but when he couldn’t come up for the match against Hawthorn we decided to get it scanned,” Burgess said.
“The scans showed a fracture there, unfortunately it looks like a 3-4 weeker for him.”
Amon was a late withdrawal from last Thursday’s match against Hawthorn. He has played in 8-games this year.