Four years on and the South Sydney winger is pinching himself knowing he will line up with the Australian side and play in his grandmother's country of birth in front of family members, including Uncle Bernie, who still live in PNG.

Before his Australian debut in May, PNG officials approached Johnston and asked if he would consider playing for the Kumuls, given his grandmother Mary Brown was born in PNG and grew up in Lumi, a small district in West Sepik Province.

Johnston's grandfather Francis met Mary while in PNG as a missionary worker. The couple fell in love and moved to Australia before having Johnston's mother in Queensland. The 20-year-old is very close with his nan, who lives just a few kilometres away from Johnston in Kingsgrove and is extremely proud of her grandson

"We're pretty tight, I think I'm her favourite grandson," Johnston said. "She comes to a few games but she gets scared from the contact. She's always screaming 'Get off my grandson'. She tells me I should stop playing even though she's proud. I say to her 'C'mon Nan, I'm getting paid to do this' to which she says 'Ah, ok'."

Johnston is particularly excited about playing in front of his Uncle Bernie and "too many cousins to count" in the green and gold as opposed to NSW colours four years ago. "I was looking out for them at the airport but I didn't see them," Johnston said. "I went to his [Uncle Bernie's] place, met all the family here which was pretty cool. He's a doctor and the family here are all doctors. They're doing well for themselves."

James Segeyaro's well documented fall-out with PNG officials is one thing, but if you ask most people here, they will say Johnston is nothing but Papua New Guinean. "Playing in front of the PNG crowd, they're all going crazy because they know I'm from PNG and I have that heritage," Johnston said. "It's just really surreal how much they know me. It'll be great to play in front of them. It wasn't really a hard decision, but I was very respectful and thankful for being asked to play for PNG that's for sure."

A new generation of NSW under-16 players were lucky enough to have a session with the Australian side on Friday afternoon on Sir John Guise Stadium, the venue for Saturday's match which kicks off at 7pm. They tackled and ran at their heroes, looking to impress coach Ivan Cleary.

Johnston took a moment to soak in just how far he had come, after being on the other side four years ago as an NRL hopeful. "That's probably something they'll never forget because I have such great memories from that trip [to PNG] that I'll have for the rest of my life," said Johnston, who scored 21 tries in his debut year before following it up with 17 this season.

"After looking up at those players, to now be a part of it has been a great experience for me and I would take it with both hands."