Parramatta prop Luca Moretti, 26, will debut for PNG against Lebanon in Saturday's World Cup opener in Port Moresby.
Coach Jason Demetriou has named him to start in the front row.
Moretti played for Italy at the last World Cup, qualifying through his father's ancestry.
His mother Julia and her sisters were born in PNG; grandfather Kevin Broadley was a government lawyer there before the country's 1975 independence from Australia.
"He (my grandad) was in tears when I told him I was selected," Moretti told AAP.
Kumuls great Adrian Lam coached Moretti as a junior, while Eels teammate Jack de Belin's stories of PNG's devoted fans helped inspire him.
Moretti and de Belin are the only PNG forwards to play in the NRL this year; Lebanon also have Eels centre Jordan Samrani.
"He's not got a target on his back, he's got a target on his head," Moretti said of Samrani.