Jarome Luai has marked his first match in Papua New Guinea with a dominant World Cup win as Samoa dismantled the Kumuls in a 64-6 thrashing.

At the National Football Stadium, where Luai and teammate Brian To'o will call home when they join the PNG Chiefs in 2028, Samoa survived an early scare to keep their unbeaten start to the tournament intact.

The local fans unfurled banners for the Chiefs-bound pair on Saturday, where Luai recorded four try assists and To'o crossing for a try.

Samoa will play Tonga in Sydney next Sunday, when both sides will look to guarantee their passage to the semi-finals as Group B/C winners.

But Samoa will head there having received a thorough test at the hands of the Kumuls, in dizzying heat and humidity in Port Moresby.

PNG could only name an 18-man team list due to injury and illness and then lost Jack de Belin midway through the first half.

The Kumuls were arguably the better team for much of the opening 40 minutes, despite conceding to Sua Fa'alogo when the winger race over on the left after just 70 seconds.

Stephen Crichton missed the sideline conversion, but the Kumuls rose to the occasion and hit back through a converted Bailey Biondi-Odo try.

The excitement was palpable and one of the loudest cheers from the 15,088-strong crowd came when PNG five-eighth Gairo Voro hammered Luai.

That noise turned up a notch when PNG thought they had another try when Rob Derby got his hand to an in-goal grubber soon after Biondi-Odo.

But the winger failed to ground it cleanly and to compound the Kumuls' disappointment, Spencer Leniu crashed over soon afterwards and PNG lock de Belin was taken off with injury.

Crichton added a third Samoa try shortly before the end of the half, which descended into an all-in melee when Leniu and Luai tipped Voro into the ground.

With Samoa leading 14-6 to start the second half, the depleted Kumuls needed to conjure something special to get themselves back in the game.

But on one of Samoa's first promising forays forward, PNG fullback Morea Morea failed to catch a bomb and the deflection made its way to Fa'alogo, who breezed over in the 45th minute.

From there it was all one-way traffic, as the Kumuls wilted against a side stacked with NRL talent.

Hamiso Tabuai-Fidow grabbed a second-half double as Francis Manuleleua, Shawn Blore, Ronald Volkman and Izack Tago went in for Samoa.

The result was PNG's heaviest defeat since a 76-12 loss to New Zealand at the 2010 Four Nations.

Jason Demetriou's side will need to beat England in Wollongong on Friday, and hope other results go their way, to have any hope of reaching the knockout stages.