A CALF injury suffered in the WAFL on Saturday will delay Harley Bennell's debut for Fremantle but coach Ross Lyon says the boom recruit was never going to be picked for round one. 

Bennell was the standout Fremantle player with four goals and 23 disposals in Peel Thunder's eight-point loss to Subiaco.

However, Lyon confirmed on Monday that the former Sun had pulled up sore with a calf problem.

Lyon said the severity of the injury was unclear, but it had no bearing on Fremantle's team to face the Western Bulldogs on Sunday at Etihad Stadium.

"Unfortunately Harley has strained a calf coming out of Saturday's game so he'll miss a number of weeks, how long that is we don't know," Lyon said on Monday.

"He's worked incredibly hard. We're really disappointed. Everything was on track.

"But Harley was never going to play. We said he was going to play round two and that was the plan.

"I spoke to Harley yesterday. He's in a good frame of mind. He's determined. He's made great inroads here. He's stacked a lot of good moments. He needs to stack a lot more good moments and keep his focus.

"We've got full faith in Harley that he'll do that. We've got to find a solution for him. It's not unusual but calves can be tricky."

Bennell hardly trained with the Dockers' main group post-Christmas as he was on a carefully managed 10-week program to build up strength in his calves.

He had suffered ongoing problems with his calves during his five seasons at Gold Coast and missed a number of games due to calf strains.

Only once in five years at AFL level has he played every game of the home and away season. He has missed seven games in each of his past three seasons.

Lyon had been firm throughout the summer that Bennell was unlikely for round one but his form in his only NAB Challenge match and the WAFL on Sunday suggested he would be fully fit to face the Bulldogs. 

Bennell gathered 17 touches and kicked a goal in three quarters of work against Geelong a fortnight ago before dominating for Peel on Saturday.

Now he will miss round one and will likely miss the Dockers' round two clash with his former side Gold Coast. 

Lyon said his side had no other major injury concerns. The Dockers will be without star ruckman Aaron Sandilands against the Bulldogs after he was suspended for one week following a rough conduct charge in the Dockers' first NAB Challenge clash against Richmond.

Lyon confirmed that Zac Clarke is likely to partner Jon Griffin in the ruck after a solid performance in the WAFL on the weekend.

But he said it was unlikely any others had done enough, suggesting that youngsters such as Alex Pearce, Lachie Weller, Connor Blakely and Ed Langdon would have to string together some good form at WAFL level to force their way into the team.