Port Adelaide superstar Zak Butters' injury has been confirmed as a high-grade syndesmosis by the club after he had scans on Sunday.
Butters sustained the ankle injury in a marking contest during Port Adelaide's loss to St Kilda at Marvel Stadium on Saturday.
The 25-year-old's ankle was caught underneath another player and twisted awkwardly before he was helped off the ground by the trainers.
He will have surgery on his ankle in the coming days.
Port Adelaide has not confirmed the injury timeline, but said Butters will miss at least four weeks.
The Power had a litany of players fall to injury during the match, with star key forward Mitch Georgiades to miss at least one week with a concussion.
Defender Lachie Jones has been cleared of any serious internal damage after sustaining a heavy knock to the ribs.
Luckless utility Jack Lukosius' poor run with injury continued as a baker's cyst on his knee didn't allow him to finish the game. Both players' availability will be assessed during the week.
Port Adelaide has a must-win match against an in-form and ladder-leading Fremantle side next round.
The Power need to win to keep their season alive.
