Rayner's hopes of playing last year were abruptly cut short in March, with the former No.1 pick sidelined for the entirety of his fourth season in the AFL.
That match will fall over a year from when Rayner sustained his season-ending knee injury, with the 22-year-old having slowly worked into contested ball work late last year.
“Cam was coming up to me in the finals last year trying to convince me he could play,” Fagan said.
“That was never going to happen, but he’s joined in training pretty much from the word go this pre-season.
“He’s super fit and he’s very enthusiastic and we’re excited about the energy he brings to the team.
“He’s back into contested work now. He’s such a tough competitor and never takes a backwards step. He’ll play a really important role for the team this year and is on good track.”
Brisbane's premiership prospects will also be buoyed by the return of defender Noah Answerth, who has completed his own rehabilitation following year on the sidelines.
After requiring groin surgery ahead of the Lions' 2021 campaign, Answerth didn't feature for the Queensland club for the season.
A dazzling debut campaign three years ago and an injury-riddled 2020 campaign have given the Lions some promising glimpses into the Caulfield product, with Answerth's anticipated return sure to give Brisbane's backline a much-needed boost in the absence of recently retired veteran Grant Birchall.
"He's is as fit as I've ever seen him," Fagan said.
"Our physios, medical and fitness people have done a magnificent job to sort of get his body back into shape.
"He had some issues with his hip, groin and lower back, which are pretty tricky to sort through.
"Looking at him now he looks so strong, physically, particularly through his core, which was really important part of of his recuperation.
"He's training pretty much full time with us. We modify him a little bit in the middle of the week just to look after him. But we've got no reason to think that with a little bit of luck he'll play a full season this year and we'll get to see a player that we've all forgotten a little bit about.
"He's a very, very good player."
The Lions are also nursing key forward Eric Hipwood through his recovery from an ACL injury sustained in July.
Despite the season-ending injury, Hipwood is on track for an early return to the Lions' AFL side after initial fears suggested the 24-year-old wouldn't feature throughout this year.