Zac Clarke is in doubt for Saturday's Carlton Draught Derby due to knee soreness.

Fremantle coach Ross Lyon said the ruckman was in a race to be fit for the clash with West Coast. 

"He's got a bit of a sore knee though, so he's got to jump a few hurdles this week," Lyon said on Wednesday.

Freo does have options in the ruck department if Clarke can't go.

Jack Hannath played the first three rounds this year after playing 12 matches in 2013 and has been playing well recently in the WAFL. 

Jonathon Griffin has fought his way back from a knee reconstruction and has been in tremendous touch for Peel Thunder, averaging 29 hit-outs in the last 10 matches, including 47 hit-outs last weekend. 

The ruck duel will be pivotal on Saturday. Fremantle and West Coast are the number one and two ranked sides in the AFL for total hit-outs per game. 

The Eagles have selection dilemmas of their own trying to fit Dean Cox back into the line-up after a two-week rest.

Lyon said he was wary of the Eagles tall timber in attack but will resist the temptation to bring veteran Luke McPharlin back early from his medial ligament strain. 

"He (McPharlin) won't play," Lyon said. 

"We thought he was a bit of a chance. 

"We were quite optimistic on Sunday that he'd be right. He went backwards a little bit so we're aiming for Melbourne (next week) for him."

Matt de Boer is also a chance to come back from his knee injury this week, however it is unlikely to be in the AFL.

"He's running fit," Lyon said. 

"He (de Boer) hasn't missed too much. He would be unlikely to come straight in. But who knows - if we lost a couple, he could. It's a nice position to be in."