Michael Cheika reckons there’s been so many tight rugby Tests between Australia and Wales, they’ve become a self-fulfilling inevitability.

Anything other than a tense contest would surprise Wallabies coach Cheika when the teams meet at Tokyo Stadium on Sunday in one of the biggest pool games of this Rugby World Cup.

The tournament proper begins for sixth-ranked Australia, who know victory over fourth-ranked Wales should set up victory in their group, with winnable games against Uruguay and Georgia to follow.

Lose and a daunting quarter-final against England probably awaits.

Their pathway will hinge on fine margins on Sunday if recent history is any guide.

Just one of their last 13 clashes has featured a double-figure winning margin.

The two most relevant games when assessing this weekend’s possibilities make for dour reading.

Australia won 15-6 at the last World Cup while it was try-less again when Wales prevailed 9-6 less than a year ago in Cardiff, ending a sequence of 13 straight losses to the Wallabies.

The most recent result was all-too familiar to Cheika.

“If I remember correctly, there was a fair bit of ball movement and no one could score a try,” he said on Saturday.

“A lot of desperation but once you start having a series of close games, they almost become self-fulfilling prophecies.

“Because everyone knows that’s what’s going to happen and it seems to happen.”

Wales have named an unchanged starting XV for just the second time in their history at a World Cup.

It left Cheika to steal the headlines in the lead-up with wholesale changes to his backline, along with some passionate proclamations about the citing and ban handed to Reece Hodge.

Adam Ashley-Cooper will become Australia’s oldest-ever Test winger in Hodge’s place while Cheika has reunited his 2015 World Cup halves Will Genia and Bernard Foley.

The dropping of fullback Kurtley Beale, replaced by Dane Haylett-Petty, was described as a predictable move by Wales coach Warren Gatland and conservative one by Welsh journalists.

Cheika had a counter view.

“You’ve known me for a while, you know I don’t go the safe option ever, it’s not in my personality profile,” he said.

“We’ve got a plan and probably the mere fact that they’re talking about it means it’s already action.”

Cheika wouldn’t otherwise buy into mind games with the veteran Welsh mentor, who clearly has the ability to construct cohesive teams, he said.

“I don’t know him very well personally, I’ve only had a couple of conversations with him over the time but to be in one nation’s team without someone trying to cut your head off (for 12 years)… it’s been an unbelievably good run.

“He’s been excellent at what he’s done.”

The forecast is for showers and hot, humid conditions for the afternoon kick-off.