O'Brien, who battled testicular cancer as a teenager, has played two senior games in 2019.

He joined midfielder Sam James (shoulder) as an inclusion.

James was declared a certain starter to play on the Hampden league's biggest stage on Saturday but Eagles coach Adam Dowie will make a final call on his team, including O'Brien, on Friday night.

He said the weather, which is predicted to be wet, would play a part.

"It will depend on whether we go with a taller, running wingman or stick with a smaller type player," Dowie said.

"Tim is a really good at contested ball and a pretty hard type of player.

"We'll have a look at the ground and see how much rain there's been."

Dowie said James was put through "the best fitness test we could give him".

"He is a really important player for us and obviously really wanted to play which is understandable," he said.

"He's been a vital part of the North Warrnambool midfield now for a few years."

Dowie said James added to an already strong midfield group which includes Michael Barlow, Billie Smedts, Jett Bermingham, Luke Wines, Matt Wines and Tom James.

The Eagles' opponent, grand final specialist Koroit, brought ex-AFL listed midfielder Tom Couch in for teenager Clem Nagorcka.

Nagorcka is ineligible for the Saints' reserves side, which will also face the Eagles, because he is part of the NAB League program.

McLaren said the exciting prospect was unlucky to miss out.

"Clem hasn't played a reserves game all year. Including his two finals, he's played 11 senior games," he said.

"As a bottom-age under 18 player, he's done really well to play for that long and contribute like he did.

"He's pretty unlucky. He's been quite good for us at times.

"He was terrific (taking the news) tonight. I am sure he was disappointed but each year we've had one or two or three players who have been in that boat for different reasons."

Teenager Connor Hinkley is the only Koroit player preparing for his first senior grand final while Tom Couch, Rhys Raymond and Jack Gleeson are chasing their first flags with the Saints but have tasted premiership success with other clubs.

"Connor is really looking forward to it, we didn't specifically tell him he was in as his form has been really good," McLaren said.

"He would've known he was playing. He is a nice, relaxed boy Connor and he'll take it all in his stride.

"He's a very measured customer."

Jeremy Hausler and Dallas Mooney are the only two Saints aiming to win six straight flags.

McLaren said it was a special feat they were closing in on but the playing group was more focused on helping those who have missed out or were new to the club win one.

B: Alex Pulling, Dallas Mooney, Timothy McPherson

HB: Sam Dobson, Connor Hinkley, Lachlan Rhook

C: Jack Gleeson, James North, Thomas Couch

HF: Brett Harrington, William Couch, Liam Hoy

F: Damian O'Connor, Jarrod Korewha, Benjamin Dobson

R: Jeremy Hausler, Todd White, Tim Martin

Int: Rhys Raymond, Jayden Watson, James GowEmg: Clem Nagorcka

In: Thomas Couch

Out: Clem Nagorcka

B: Jackson Grundy, Thomas Batten, Will Scriven

HB: Luke Wines, Adam Wines, Darcy Keast

C: Bailey Jenkinson, Sam McLachlan, Sam James

HF: Matthew Wines, Thomas O'Leary, Tom James

F: Jarryd Lewis, Joseph McKinnon, Samuel McKinnon

R: Benjamin Mugavin, Michael Barlow, Billie Smedts

Int from: Jordan Dillon, Lewis Holland, Tim O'Brien, Jett Bermingham, Jackson Couch

In: Tim O'Brien, Sam James