With defending champions New Zealand to come on Friday and a defeat to France already against their name, Adrian Lam's Kumuls knew this was a must-win if they were to have a realistic chance of taking the third spot in Group B.
Improving Samoa never gave them a chance of doing so, though, with Matt Parish's side showing more of the flashes they did in losing to New Zealand a week ago. A defeat of the Kiwis must now follow if PNG are to have any hope of progressing.
For as poor as they were Samoa were just as impressive, especially considering injury meant they only had 18 players to select from.
They face France in their final pool game and will be growing increasingly in confidence after a seven-try display which included an Antonio Winterstein hat-trick.
If they can now beat the French then second place and an easier quarter-final - likely to be against Fiji - awaits, but Parish will be more than happy that his men appear to be light years away from the group which were beaten 52-16 by the England Knights in a warm-up game.
Having been so solid against France last week and conceding just one try, it was surprising to see the Kumuls breached after just 67 seconds.
Larsen Marabe lost the ball in a loose carry and in the subsequent set Suaia Matagi burrowed his way over, with Anthony Milford converting.
Knowing they needed a good start to harness the support of the crowd - biased in their favour owing to links between PNG and Hull KR - Papua New Guinea were struggling and a second try followed with 10 minutes gone as Tim Lafai flicked a pass out to Winterstein.
That both of those scores came off dropped PNG ball told its own story and a third error duly led to another four- pointer as Pita Godinet was on hand to convert some good footwork from Joseph Leilua.
Milford kicked his second goal and then went close to a try and he beat six would-be tacklers only to be scragged down on the line, before Papua stirred in the 24th minute, Josiah Abavu having a try wiped out for a Menzie Yere forward pass.
It was nothing more than a fleeting spell with the ball, though, and the Lafai-Winterstein combination clicked again within 60 seconds to give the latter his brace, before PNG imploded entirely just before the break as forward Jason Chan tried a kick which served only to give Ben Roberts a free 60-metre run to the posts. Milford goaled and Samoa led 28-0 at the break.
Roused at half-time Papua at least opened the second-half scoring as a strong run from Josiah Abavu sent in Jessie Joe Nandye, but even though the Samoan intensity had dropped, they still had enough to get over through Sauaso Sue on the hour mark.
Knowing that they had little left to play for PNG at least tried to make things happen and were denied a second score when willing full-back David Mead's try could not be given because of an obstruction in the build-up.
Those in a crowd of just under 7,000 were left disappointed again as replays showed Nandye did not ground as he reached out to the line, before Winterstein rounded things off as he got to Roberts' kick with a minute left.