FREMANTLE will back its versatility in defence to handle star Hawthorn forwards Nick Watson and Jack Gunston in Thursday night's qualifying final after the pair combined for eight first-half goals in the last clash between the teams. 

The Dockers have confirmed they will make at least four changes for their first qualifying final since 2015, with important forwards Murphy Reid, Jye Amiss and Sam Switkowski all returning alongside defender Heath Chapman.

While small defender Judd McVee handled the bulk of the work against Watson back in round nine, it was key defender Brennan Cox who stepped up to contain Gunston in the second half of that clash.

With Cox sidelined with a calf injury, Longmuir said it would be either captain Alex Pearce or key defender Oscar McDonald lining up on Gunston, but versatility and support up the ground would be critical for the backline.

"We'll have a certain matchup for Gunston and some of their players, but we'll need to take care of them as a back six," Longmuir said on Tuesday.

"And then we need to make sure we defend as an 18 to make sure that they're not getting free-flowing ball moving into them.

"So 'Chappy' coming back into the side gives us good flexibility, showing that he can play on talls and smalls and he can play high and play deep. So we feel like we've got some good flexibility there.

"We've got to make sure we don't just focus on the one player as well because (Mitch) Lewis and (Mabior) Chol have been doing a really good job down there as well."

Watson shapes as a difficult match-up for the Dockers, who have been vulnerable at times against small forwards and conceded five goals in their most recent match to Carlton’s Francis Evans.

McVee did hold the Hawthorn superstar to four disposals and 0.1 after half-time in round eight, however, with better support up the ground following the main break. 

"(Watson) is a unique match-up. He goes into the midfield at times and flips forward out of there as well, and clearly he's got some good speed," Longmuir said.

"So not only do you need someone with a bit of speed, but you need someone with really good positioning to stop him getting goal side.

"Good teams cause headaches for the opposition, right? I'm sure we're causing a few for them, and they've obviously got a lot of players who can cause headaches for us.

"You go into a game with a plan and then a second plan and sometimes a third plan."

The opportunity to potentially play in Fremantle's maiden premiership is a factor that looms over this finals series, but Longmuir said he did not need to use it as a source of motivation.

The team has produced a club-record 19-win season by following a 1-0 mantra, and the coach backed his team to stay in the moment this week, even if everyone was aware of the significant opportunity ahead.

"If there's someone at the footy club that doesn't see that carrot, well then you're probably in the wrong game, right?" he said.

"All of our players know what's on the line, and we just need to make sure that we use whatever motivation that gives us to give it all to your next moment.

"Some players will see it as a stimulus and some players will maybe see it as a distraction and we'll work through that.

"The way to win premierships is to win games of footy, and you win games of footy by winning more moments than the opposition.

"So we all know what's on the line, but we've just got to make sure that we give our best at each moment and the next moment's the most important one."

Fremantle used its lead-in to finals to manage players within games and give certain players a week off, with Pearce and Shai Bolton among those who were managed as other stars benefited from reduced game time after a top-two spot was sealed.

Longmuir said the Dockers would know how successful that strategy was in time, but the team entered September feeling fresh.  

"We'll look back in five weeks and see if it was the right way to go about it," the coach said.

"We had no issues in managing the guys we managed in the Melbourne game and the Carlton game.

"They had stuff that they needed to manage, and guys like JT (Josh Treacy) and Luke (Jackson), we've been able to give them a game off within the back half of the season without them having a week off, if that makes sense.

"But they should feel fresh. They should feel ready to go, and we'll put our best foot forward."