Kalyn Ponga will wear New Zealand's black jersey for the first time on Thursday evening against Australia, having switched from the Kangaroos.
Kiwis coach Stacey Jones says Ponga brings confidence after a strong finish to the NRL season with Newcastle, where he helped lead the Knights to a grand final.
Jones says New Zealand faces a growing challenge to retain players eligible for other nations. "We're in a battle to keep players with us that can play for Samoa, Tonga and other Pacific nations," he told media before the match.
Former Kiwis captain Dallin Watene-Zelezniak has recently changed allegiance to Tonga, while Jacob Laban will represent New Zealand after his Samoan chief father approved.
Jones sees this year's World Cup as a chance to strengthen New Zealand's standing, with more players raised in Aotearoa choosing other national teams.
He said international competition is strong and teams must do the fundamentals well. "There's no secret about rugby league, you defend well and you run hard with the footy, you generally come out on the top, so we'll do the best in that area, but we know that they're world- class teams."