Keano Kini is expected to replace Kalyn Ponga at fullback after Ponga broke his arm against Australia on Thursday.
Friday scans confirmed the fracture, which requires surgery; Ponga had played on for about 20 minutes.
The NRL Physio estimated at least a month, possibly two, for recovery; only four weeks remain if New Zealand reaches the final.
Ponga is unlikely to play again in the tournament.
On his New Zealand debut after switching from Australia, he scored twice and ran 253 metres before the Kiwis lost to Australia's late comeback.
Before the scan results, coach Stacey Jones said, "He's OK. He's upbeat." He added that Ponga still wanted to be involved.
Charnze Nicoll-Klokstad is also in the wider squad, while Phoenix Crossland could return for the semi-finals and final, subject to IRL approval.
New Zealand may add a player despite naming no shadow players and expects to decide Ponga's status later this week; no other injury concerns are reported.