FREMANTLE ruckman Aaron Sandilands appears a certain starter for Friday night's semi-final against Geelong at the MCG, and coach Mark Harvey is confident he will be able to take centre bounces.

Sandilands has been receiving up to 12 hours of physiotherapy treatment on his injured left knee each day this week, and he told Channel Seven on Tuesday night that he "should be good to go in the ruck".

Harvey said the club would get an idea of how much ruck work Sandilands is capable of doing once the side arrives in Melbourne, but his progress this week had been encouraging.

"Every minute, every hour that goes by, the response has been really positive so that's all we can judge it on at the moment," Harvey said from Subiaco Oval on Wednesday morning.

"Naturally, we'd probably like to see in the next 48 hours what he can do, so at some stage we'll have a look at him over in Melbourne.

"If you have a look at a lot of Aaron's ruck duels, no matter where they are, he doesn't jump a hell of a lot. So once again we've got to just see how quickly this injury can come up as to what he can do."

Sandilands had to be kept on the ground against Hawthorn last Saturday to stop his knee seizing up, and Harvey said the dual All-Australian may again get his rest in the forward line.

"We'll probably keep him on the ground a bit longer which should be a headache for Geelong," he said.

Fremantle will take a squad of 25 to Melbourne on Wednesday night, with an eye on the showers forecast for Friday.

The side has a six-day break following last Saturday's 30-point elimination final win over Hawthorn, but Harvey said that was less of a worry, given up to half of his side would not have travelled in more than a month.

The coach said retiring midfielder Paul Hasleby and x-factor forward Des Headland were in the selection mix, while Rhys Palmer is also available after a two-goal, 21-possession performance for East Fremantle.

"There's conditions, what we think is right [and] we'll have a look at Geelong's selection, so there's a couple of things to take into consideration," he said.

"In a lot of finals you need an x-factor. Now the unassuming player it can be at times, or it can be the guys that have had the dominance of the season, so we have got a couple of players that we'd like to think are x-factors.

"Geelong might have a few more, but if we can control them then we'll see what happens."

Adam McPhee has emerged as an important tagger in Fremantle's structure, and with Ryan Crowley back in the side Harvey has two proven run-with options for Friday night.

He said if Fremantle could stop Gary Ablett from kicking goals and limit his creativity, the side would be "in the ballpark".

"Now we all know that he's a genius, we've got to find a genius to play on him," Harvey said.

"They had a tough game on the weekend, they're expected to play in a grand final [and] it's their backyard.

"We managed to beat them early in the year. It doesn't mean anything but at least we have the confidence and the knowledge [that] we can match it with them."