FREMANTLE coach Ross Lyon says star midfielder Nat Fyfe is nursing a groin injury separate to the corked quad he suffered in round 15 against Hawthorn.

Lyon told Channel Seven on Tuesday night that Fyfe would not play against Greater Western Sydney at Domain Stadium on Sunday.

It was assumed that the soreness Lyon referred to in the interview was the cork that Fyfe had been battling for three weeks.

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But Lyon clarified on Friday that the Brownlow favourite was actually battling a groin complaint, and although he was hopeful it would only keep Fyfe out for a week, it could take longer.

"The situation is he (Fyfe) has got a bit of a groin," Lyon said.

"We're going to build his strength. We're not resting him.

"He's actually got a legitimate injury.

"We're treating it as one week. Obviously, if it doesn't come up next week then it will be a two-week injury.

"Hopefully it's one week, but if it needs to be two it will be two. That's what I said to the doctor - if it needs to be six weeks, it will be six.

"But we're optimistic that hopefully it's less rather than more."

Fyfe was absent from training on Friday. Experienced midfielder David Mundy was also absent with what Lyon said was a migraine.

Mundy trained on Wednesday and the coach said he should line up on Sunday.

"We expect him to play," Lyon said.

"I'd be really disappointed if he didn't play."

Lyon confirmed that Clancee Pearce had been omitted for form reasons, rather than for the shoulder injury he suffered last Saturday against Richmond.

Young key forward Matt Taberner was also omitted on Thursday night. Lyon said the 22-year-old was still developing and was just experiencing the normal ups and downs of a young key position player.

"He just needs to go and train well," Lyon said.  

"We don't think he's been at his best, putting his best foot forward. We know he's a lot better than that. He's a wonderful young player, but that happens with young players, they go up and down.

"The earliest draft picks take time. He's ahead of schedule really as a rookie list player in his third year. He's going really well but it's not unexpected."

Key defenders Alex Silvagni and Michael Johnson trained with the main group on Friday after doing some sprint testing prior to the session. Both are working their way back from hamstring surgery and are closing in on returns.

Zac Dawson has been added to the squad this week. Lyon was asked whether Luke McPharlin required a rest but he said the club was managing the veteran pretty well.

Lyon said it was more than likely they would field a debutant this week but he could not confirm which one Lachie Weller, Connor Blakely or Ed Langdon would play.

"It's more likely than unlikely," Lyon said. 

"But again, we've just got to get our whole mix (right). If Mundy didn't come up, that would change the whole mix, but it's more likely (he will play).