Australian loose forward Cornelsen set to face Wallabies as a Brave Blossom

Growing up with one of Australian rugby's most famous names and playing with now-Wallabies star Tom Banks, Jack Cornelsen certainly couldn't see this coming.

In fact, even just a couple of years ago, this wasn't on Cornelsen's radar.

But on Thursday the 27-year-old will almost certainly be named in the Brave Blossoms team to face the Wallabies in Oita on Saturday.

Good judges are even tipping the versatile forward to start, most likely in Japan's No.6 jumper.

"It would be huge. If I do get the opportunity, it would be unreal," Cornelsen told AAP on Wednesday.

"Growing up it wasn't the path I imagined that I'd have taken but quickly how things can change.

"I'm obviously really grateful for the position I'm in now and it's not a position I would have seen happening a few years ago."

Certainly not when he first received a call from Robbie Deans to join the former Wallabies coach at the Panasonic Wild Knights in Japan's Top League in 2018.

Overlooked for an Australian Super Rugby contract, despite starring in two Brisbane club premierships with the University of Queensland and climbing the ranks with Banks and others including Tate McDermott, Cornelsen felt he had nothing to lose joining Deans.

But he never dreamed it would lead to him turning Japanese.

"First coming over here, it was just for the experience," he said.

"I was only playing club footy over there back in Brisbane so I just came over here to see what the go was. I had no real long-term plans.

"But the longer I've been here, the more I've loved it. So I can definitely see myself staying here long term.

"I'm a big fan of the food so that helps."

The son of Greg Cornelsen - the ex-Wallaby who famously bagged four tries against the All Blacks at Eden Park in 1978 - credits Deans' one-percenters for helping launch his international career.

He's also lapped up lineout advice from world-class locks like Sam Whitelock and George Kruis and tapped into the vast experience of champion flanker David Pocock to develop into one of Japan's most versatile forwards under coach Jamie Joseph.

"That definitely has helped me," Cornelsen said.

"I've been between lock and back row so anywhere there I'm comfortable with.

"But I'd play on the wing if they asked me to."

Deans declared Cornelsen Test-ready back in March.

Right on cue, the late bloomer made his "pretty cool" Test debut against the British and Irish Lions at Murrayfield in June.

But running out to face the Wallabies would be next level, surreal even.

"I don't really know how to put it into words. The excitement would be up there," Cornelsen said.

COVID-19 will prevent his father from being at the game.

"It would have been unreal if him and mum could have gotten over here and watched the game," Cornelsen said.

"But they'll be watching at home with some excitement as well, probably more nervous than me.

"Dad's always been supportive of the path I've gone on now. He's backed the decision to come over here and hopefully he'll be wearing red and white on the weekend."