FREMANTLE superstar Nat Fyfe will miss Sunday's clash against Geelong at Simonds Stadium with a bruised sternum after being withdrawn from the Dockers' 25-man squad on Friday afternoon.

Fyfe has been replaced in the extended squad by defender Cam Sutcliffe, with the Dockers to trim their squad to 22 at 5pm AEST on Friday.

The decision to withdraw Fyfe from the squad was made after the team's training session on Friday.

"The medical advice was that Nat be ruled out this week," football manager Chris Bond said in a club statement.

"We will monitor Nat throughout next week before making a final decision but we believe he will be right to play in the St Kilda game."

Fremantle had a bye in round 13 and last played on June 10, losing to the Brisbane Lions at the Gabba, with Fyfe gathering 18 possessions and kicking two goals in a quieter than normal performance.

The champion onballer wore a protective chest guard in that match, but coach Ross Lyon this week played down any concerns around the Brownlow medallist's fitness.

"Clearly he's had some bruising. But that's all it is. There's no fractures. There's just been some bruising," Lyon said.

"It's not something I've engaged in him with. And Nathan doesn't like to make a fuss about it."

The Dockers will be missing ruckman Aaron Sandilands for Sunday's clash because of a hamstring tendon inflammation.

Small forward Hayden Ballantyne has been named on the extended bench for what would be his first AFL match this season after ripping a hamstring tendon in the Dockers' final JLT Community Series match.