GWS will contest a third preliminary final in four years when they play Collingwood at the MCG .

They will start outsiders in front of what will be a pro-Pies crowd.

But this time they will go in with the physical, mental, emotional and big-match maturity they lacked in previous years.

With their bullying of the Bulldogs in an elimination final and the steel they showed in closing out last week's semi-final when they were besieged by Brisbane, GWS appear to have arrived as a battle-hardened finals outfit.

The relatively scrawny frames of the club's remaining foundation players, who joined GWS as teenagers, have been replaced by bodies up to 13kg heavier than they were in their inaugural season in 2012 when bigger sides monstered the newcomers.

"From the early years when I first got here they were young kids, there was no facial hair," said Mumford who joined GWS after the 2013 season.

"To see them grow into men and fill out their body that was always going to take time.

"We've got so close a few times and we've played in some big finals.

"It's only going to help us going into another massive final this weekend."

Barrel-chested ruckman Mumford provided a much needed imposing physical presence to support the large cast of talented but much slighter midfielders in the formative years of the club.

The former Geelong and 2012 Sydney premiership player retired after the 2017 season with a foot injury.

He returned this year after winning a couple of professional boxing bouts in 2018, but the physicality of the game has continued to take a toll on the 33-year-old big man's body.

Mumford admitted he could barely move after the game against Brisbane, though he felt good a couple of days later

A loss at the MCG on Saturday could bring down the curtain on the career of one of the code's most colourful characters.

"I actually don't know myself yet," he said.

'Me and (GWS head coach) Leon (Cameron) are going to sit down after the season and work out then as to whether my mind is still there, my body is still there

"I think that going to be the biggest thing whether my body is still there to do it,"

Saturday brings another formidable challenge in the shape of Collingwood's All-Australian ruckman Brodie Grundy.

'He doesn't really have too many things that he doesn't do well." Mumford said.

When GWS beat Collingwood in their one meeting this season, Mumford was the secondary ruckman behind Dawson Simpson but come Saturday he will have to shoulder most of the load.

FROM BOYS TO MEN - HOW THE GWS GIANTS HAVE GROWN

* Jeremy Cameron: 2012 weight 89kg - 2019 weight 96kg

* Toby Greene: 2012 weight 77kg - 2019 weight 83kg

* Nick Haynes: 2012 weight 77kg - 2019 weight 90kg

* Adam Kennedy: 2012 weight 73kg - 2019 weight 80kg

* Adam Tomlinson: 2012 weight 87kg - 2019 weight 96kg

Australian Associated Press