New Zealand must beat the Wallabies at Perth Stadium on Saturday for a chance at winning the Rugby Championship, a week after securing the bilateral Bledisloe Cup with a 33-24 win at Auckland's Eden Park.
Williams was born in New Zealand but lived in Perth up to the age of 16, playing rugby union on Saturdays and rugby league on Sundays.
With fellow prop Ethan de Groot injured, the 25-year-old will be expected to train hard, step up and slot into Scott Robertson's side as directed.
Being a tour guide for his teammates is a lower priority.
"(I have) a lot of family here, a lot of family and friends. But a great coach once told me, when you sign your arrival card make sure you tick business, not holidays," Williams told reporters today.
"We're here for business and we do that first. We're in the middle of the city, and I'm from way out, so Uber's a bit too expensive.
"But we've got a day off on Wednesday, so I think we might hit Scarborough Beach. We'll swim or something."
Had Williams lingered longer in Perth he may well have been absorbed into the Australian rugby system as a talented junior.
Instead, he returned home, earned a scholarship to an Auckland school and then a contract with the Canterbury Crusaders during Robertson's hugely successful tenure as head coach of the Super Rugby team.
Williams said the Wallabies were doing just fine without him under Joe Schmidt, who was an All Blacks selector and assistant coach when the prop earned his first call-up to the squad in 2023.
"Joe Schmidt's a great man. He's a great coach," said the hulking 1.96m prop.
"They've had a big year. They're battle hardened. They've had a good series against the Lions, played South Africa, Argentina, and they're confident.
"So they should be. They deserve to be.
"I think for us it's a cool challenge. We want to play them at their best, and I'm sure they want the same."
The Wallabies may be close to their best with the addition of lock Will Skelton and loose forward Rob Valetini, two of their biggest bodies and strongest ball carriers.
Skelton missed the last three Rugby Championship matches while on club duty in France, while Valetini missed Eden Park with a recurring calf problem.
Both are available for Perth and could present a different challenge for the visitors on match day.
"There are a few big bodies that can be thrown at us," said Williams.
"But we have to wait and see.
"Obviously we just think that (Australia) are going to be better in areas that we already know that they're good at, whether that be at the break-down, their carry and the likes.
"We're expecting them to bounce back after a loss, as most teams do."
