The Dockers tackle the Sydney Swans on Saturday night and they are still unsure what combination they will use in the ruck department.
" I think 'Daws' (Zac Dawson) played a really good game pinch-hitting in the ruck," Johnson said of last week's clash with Collingwood after Griffin went down with a season-ending knee injury.
"Whatever Ross (Lyon) brings up and whatever Ross wants, the players will put their hand up and do whatever they can to play their role for the team."
The ruck responsibility will fall mainly onto the broad shoulders of 21-year-old Jack Hannath, who will play just his fourth game on the weekend.
Johnson said his teammates have a lot of faith in him.
"He's got a big test this week and next week. But being a teammate I'll back him in.
"All he needs to do is play his role for the team and get a couple of taps down to the midfielders."
Johnson said the side was very confident travelling to the SCG, having won two of its last three at the venue.
"I think we’re confident with the way we’re playing at the moment.
"The game plan has been working for us.
"I know injuries have hurt us, but we have players who can come in and play those roles."
"We’ll go over there and match it against Sydney."
Fremantle hopes to utilise the expertise of assistant coaches Mark Stone and Brett Kirk, both of whom have been heavily involved with the Swans prior to their tenure in the west.
"They’ve been there for a number of years, and Kirky’s played with a number of those players, so no doubt the players will be in their office all week this week trying to get an insight into a number of players.
"That's a bonus for us to have those two guys on our coaching staff to help us out."
Fremantle regains the services of Nathan Fyfe after missing the last two weeks with suspension, but will still be without Stephen Hill, who is sidelined until round 10 with a quad injury.
Johnson said the in-form Michael Walters could push up into the midfield.
"I guess that's another string to Michael's bow, not just a forward pocket kicking goals.
"He can play a number of roles, which is good for the team.
"He's worked really hard on his running.
"The way he finds the ball, the way he crumbs, the way he finds the goals, it's very special to have a player like him on our list."
