FREMANTLE is counting the cost of Sunday's 40-point win over Adelaide with All Australian defenders Luke McPharlin and Michael Johnson to spend extended time on the sidelines.

Johnson was subbed out of the game at half-time with a suspected medial ligament strain and Fremantle has revealed on Tuesday that he will miss four to six weeks after coach Ross Lyon initially suspected it may only be two to four.

McPharlin also injured his knee during the first half of the win over the Crows, but following scans on Monday the veteran has been ruled out for three to four weeks.

After playing with an unchanged side for the past two matches the Dockers depth is going to be severely tested in defence.

Lee Spurr believes the group can cover the losses of McPharlin and Johnson.

"We have still got Zac Dawson there, very experienced," Spurr said.

"Garrick Ibbotson at 100 plus (games), Paul Duffield a lot of games.

"A lot of the players will stick together and stand up."

Fremantle also face a nervous wait on Tuesday when Hayden Ballantyne fronts the AFL Tribunal for his bump on Adelaide's Matthew Jaensch. 

The Match Review Panel referred the matter straight to the Tribunal as it was understood that Ballantyne's 87.5 carryover points from his suspension for two incidents in round five against the Sydney Swans would have affected the MRP's grading of the bump.

Ross Lyon said on 6PR on Monday night that he thinks the rules on these types of incidents are murky. 

"It's certainly left it open to interpretation, the MRP can be quite narrow, so they’ve put it in the too-hard basket I would think," Lyon said.

"I really liked how he went about competing and trying to win the ball. 

"I think the overall rule is very confusing and grey. 

"The spirit of the game is about competing, isn't it? And it's about intent and either malicious intent, going the bump, or going to compete.

"I certainly would like to see similar events judged in the spirit of the game."

Spurr also supported the way Ballantyne had attacked the contest. 

"We support fully the way Hayden plays and how way he goes about it, his passion when he plays, and his intensity," Spurr said. 

"He really ignites the team with that intensity and the way he attacks the ball so I think as long as you make the ball your object you'll be OK"