On a day when defending champion Brett Rumford set the pace with an eight-under-par 64 at Lake Karrinyup, Forrest hit the ground running in his first competitive outing in 2018.
The 24-year-old carded a solid 69 - it contained four birdies and just one bogey - to sit joint-21st in the tri-sanctioned event on Australia’s west coast.
It was a promising start for Forrest on his debut in the unique tournament, which has two cuts before reaching a series of six-hole knock-out matches.
The top 65 and ties after 36 holes make the first cut before the field is then reduced to just 24 players after three rounds.
Forrest hasn’t played since the Joburg Open in December, having also teed up in the Australian PGA Championship just before that.
He was out in Dubai last month as part of his preparations for the start of the Challenge Tour campaign in mid-March and only secured this unexpected European Tour outing at the weekend.
The Craigielaw player was 31st reserve at the close of entries and only fourth reserve when he travelled out to Dubai last Thursday night.
He then stayed there for a couple of days before travelling on to Perth and only got the confirmation at lunchtime on Sunday before arriving in Perth late afternoon on Monday.
Forrest was joined in red figures later in the day by Bradley Neil as the Blairgowrie 22-year-old battled to a one-under 71 to sit just outside the top 40.
In an up and down round, Neil signed for five birdies and four bogeys in his first event since the South African Open last month.
Duncan Stewart, who made it to the match-play phase 12 months ago, has a battle on his hands to achieve that feat on this occasion.
That follows the Grantown-on-Spey man having to settle for a two-over 74 while Connor Syme and Thai-based Simon Yates both face fights to make the first cut following scores of 76 and 79 respectively.
Home man Rumford covered his front nine in 29 and bagged 10 birdies in total as he took up where he’d left off 12 months ago.
“Got off to another fast start,” said Rumford, who led for all three days of the stroke-play segment last year at the same venue.
“I just think there’s some golf courses just fit your eye, just suit your eye and others don’t.
“I’m inside the top 24 and that’s my only focus this week. If I lead the qualifying again, that would be a nice bonus but it’s not my priority this week and I’m playing accordingly.”
The 40-year-old leads by two shots from compatriot Jamies Nitties and Edinburgh-based former world No 1 Lee Westwood.
“The swing’s just getting better all the time,” said Westwood, who shot a 10-under 62 in the second round in Malaysia last week and opened this event with an eagle and five birdies.
“It was nice to shoot 66. I don’t think this is a tournament where you want to be playing catch-up, really.
“You want to get yourself in the mix and try and cruise through the second and third days and get into that top 24.”