Fremantle has been dealt a major blow with giant ruckman Aaron Sandilands ruled out of Saturday night's clash against Adelaide.

Dockers coach Ross Lyon revealed on Wednesday that the influential big man was battling hamstring tightness, while youngster Ed Langdon (knee) will also miss the trip to face the Crows.

"(Sandilands has) just tightened up in the hammy," Lyon said.

"It's just a bit weaker than we would like it. The scan was clear … we need to get it strong again.

"Hopefully (it's only one week), that's what we're aiming for.

"We'll bring in Jon Griffin (and ask him) to execute your role. Everyone brings something different to the table.

"Jon plays with a real passion and he's carried the number one ruck spot years ago for us when Aaron's been out and done really well, so we don't expect any different."