Port Adelaide coach Ken Hinkley concedes Hamish Hartlett's season-ending knee injury is a huge blow for the in-form defender and the club.
Hartlett ruptured the anterior cruciate ligament in his right knee in a training incident on Thursday.
Scans confirmed the 27-year-old will need to undergo a knee reconstruction, which will end his season, after the innocuous mishap.
It is a cruel blow for Hartlett, who had made a flying start to the 2018 campaign.
"Hamish will have surgery sometime in the next 24 hours ... and he'll start the long haul to playing some great football (like) he was playing at the start of this year," Hinkley told reporters on Friday morning.
"Hamish's form would've been in our best three players this year.
"It's always a bit of a blow, but when it's someone who's worked so hard to get himself established to be the player he wants to be it's a little more difficult."
Hartlett had played all five matches this year for a career tally of 153.