Australia led 22-0 at halftime after Williams and centre Joel Monaghan each scored doubles in the opening 40 minutes.
The 16,239 fans showed their appreciation when PNG centre Menzie Yere showed great hands to scoop up a Rod Griffin grubber kick off his boot laces to score in the 73rd minute.
Yere, a late inclusion for George Kepa, will long remember his try because the player he burst through was young Kangaroo giant, Israel Folau.
The scoreline will look good for PNG to take home after they lost 82-0 the last time they played Australia in the 2000 World Cup.
Replacement utility Scott Prince notched the first two touch downs of the second half to blow the score line out to 34-0 at the 55th minute mark.
Prince, who started his rugby league career with the Cowboys in Townsville, appeared like a thief in the night to snatch an intercept off Kumuls veteran Stanley Gene just two minutes into the second half.
The Titans playmaker got his second after Williams made a breathtaking 60 metre swerving run only to be dragged down five metres short with a hat-trick on offer.
PNG could not be accused of not having a dig against the world champions, showing tremendous heart to keep Australia to 6-0 in the opening 20 minutes.
With some pundits tipping the Kumuls could be smashed by 100 points they stuck it out until the 80th minute despite Australia’s relentless pressure.
Hard working Kangaroo forward Anthony Tupou grabbed Australia’s eighth try just before fulltime.
While they failed to win a game in the “pool of death” which also included England and New Zealand, PNG can head home having won the respect of many fans for the way they played the game and conducted themselves off the field.Australian five-eighth David Campese was taken to hospital after bleeding in his eye following a first half tackle by PNG forward Neville Costigan.
“He had some bleeding to his eye and some double vision so we sent him straight to hospital,” said Australian coach Ricky Stuart.
Stuart praised counterpart Adrian Lam for the job he had done preparing the Kumuls, who had the difficult task of playing the top three countries in the world.
“Being seeded in that super group is going to do them the world of good,” said Stuart.
“Adrian has done a remarkable job. They can really hold their heads high and the kids in PNG have some heroes to follow.”
Stuart said Williams’ remarkable year had continued tonight with his three-try debut.
“I don’t know if that’s a record but he’s had a remarkable year.
“Apart from his three tries he played really well.
“To get picked (for Australia) and then bag three tries, I’m sure he is a very happy boy at the moment.”
Kangaroos captain Cameron Smith joined Stuart in singing the praises of PNG, rating them close to England and New Zealand and predicting they could do well in the NRL if they continued to improve over the next five to 10 years.
“They’re a damn good football team,” said Smith.
“They show a lot of commitment and they didn’t give up. It wasn’t easy out there and we had to work hard.
“They really tested us at times when they had the football.
“I can see PNG going from strength to strength.”
Lam said he was proud of his players’ performance after last weekend’s letdown against the Kiwis.
“We got up for England because we had four weeks to prepare and the guys were devastated by the result (a 32-22 loss),” he said.
“We died in the ass a bit after that but we got up tonight because we had nothing to lose against the best team in the world.”
AUSTRALIA 46 (D Williams 3 J Monaghan 2 S Prince 2 A Tupou tries J Thurston 7 goals) bt PAPUA NEW GUINEA 6 (M Yere try J Wilshere goal) at Dairy Farmers Stadium. Referee: S Ganson. Crowd: 16,239.