With Collingwood veteran Scott Pendlebury celebrating his record-breaking 433rd game, the Eagles will have to contend with the biggest home-and-away crowd in West Coast's history.
The Eagles possess the youngest and most inexperienced list in the league and a host of their fledgling talents will be playing at the MCG for the first time this Saturday.
Reid will be playing there for just the third time.
Eagles coach Andrew McQualter revealed on Thursday the club had already leaned on their psychologist to help players deal with the big occasion.
Reid appears destined for a career filled with highlights on the biggest of stages - he just hasn't had the chance to show it yet.
With the Eagles sitting in the doldrums ever since Reid arrived as the No.1 pick at the end of 2023, West Coast have played mostly off Broadway.
That will all change on Saturday when the football world focuses on Pendlebury's special day.
Reid will be notching his 50th AFL game in the same match, and McQualter reckons the 21-year-old is built for the big stage.
"It seems so. It appears to be," McQualter said.
"When our crowd's loud at Optus Stadium, Harley plays his best.
"He hasn't had the opportunity to play in a game like this yet ... so looking forward to seeing how it goes."
Reid played the best game of his career last week when he racked up 34 disposals, 10 clearances, eight tackles, 12 inside 50s and two goals in a shock 17-point win over GWS.
The Victorian tallied 14 disposals and two goals in the second quarter alone, with McQualter rating it as one of the best quarters he's ever seen by an individual.
But it was Reid's tough work on the defensive side that pleased McQualter the most.
"He's always going to have good moments with the footy, that's the type of player he is," McQualter said.
"But when he buys into the team defensively, like he did last week, that's when we're going to make real gains."
With Jack Hutchinson ruled out for the next three to five weeks with a hamstring injury, Bo Allan will earn a recall against the Magpies.
And in a dose of good news for West Coast, prized recruit Brandon Starcevich will line up in the WAFL this weekend on managed minutes after overcoming a horror run of knee and calf injuries since featuring for Brisbane in last year's grand final.
"My gut feel is he won't be in the WAFL too long," McQualter said.