FREMANTLE tagger Ryan Crowley is likely to run with Port Adelaide captain Travis Boak in Saturday's semi-final after Dockers coach Ross Lyon suggested the in-form Robbie Gray required a different match-up.

Crowley held Boak to 22 disposals, including just five kicks, in the round 23 clash between the two sides at Patersons Stadium. The Port skipper ran riot against Richmond on Sunday, gathering 34 touches and kicking an early goal.

Meanwhile, Gray has had a phenomenal year, winning the AFL Coaches' Association Champion Player of the Year award. Gray was also a very influential figure in round 23 against the Dockers, winning 33 disposals and kicking 2.3 in Port Adelaide's eight-point loss.

Lyon said on Tuesday that Crowley was likely to go to Boak, while he expected Port stopper Kane Cornes to tag Fremantle wingman Stephen Hill. 

"We could change, but at this point I reckon Cornes will go to Hill and 'Crowles' will go to Boak," Lyon said.

"(He's a) great player Gray, at the minute. He flicks in and out of the middle. You can't tag everyone.

"Boak's their leader. He's a great player. But it could change."

Freo's star small forward Hayden Ballantyne is likely to miss after he had jaw surgery on Monday. Lyon virtually ruled a line through his leading goalkicker, saying the club had a duty of care to look after Ballantyne's health. 

Matt de Boer and Nick Suban appear the likely candidates to come into the side.

Michael Barlow will be right to play despite spending Sunday and Monday in a moon boot to protect a foot issue.

Lyon also said he was considering ruckman Jon Griffin as a potential replacement for one of Zac Clarke and key forward Matt Taberner, following the duo's quiet showing against the Sydney Swans.

However, the Freo coach said he was realistic about what developing talls could produce at any given time. 

"You've got to understand that they are young players," Lyon said. 

"Everyone wants to hang Taberner out. He's a second-year player. 

"Zac's 203cm, [a] young basketballer who came in skinny. It takes a long time to become an Aaron Sandilands-type ruckman and Matthew Pavlich-type forward, so you have to keep growing. 

"Young forwards take a long time so I would suggest he has grown, but at the end of the day, when you get to the pointy end (of the year) you can't always wait."

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