The Flying Fijians played a trump card in announcing their team for Saturday's match in Sapporo by shifting the explosive Radradra to the left wing.
It's the same position where the former rugby league star was a five-season NRL sensation for Parramatta, scoring 82 tries in 94 games until 2017.
All of the 27-year-old's Test rugby appearances have been at outside centre and he has been primarily used there at French club Bordeaux.
Reece Hodge will be marking Radradra and his team-mate Matt Toomua joked the Melbourne Rebels outside back will need a crash course in defensive play
"We'll be sending him his (Radradra's) highlights from his Eels days and letting him know he's got his hands full," Toomua smiled.
"I think there's a few guys who will have their hands full out there, especially individually.
"We've got to hunt in packs, I guess, that'll be our best chance of limiting their opportunities," Toomua said.
Fiji coach John McKee has made the switch to accommodate another French-based star, Waisea Nayacalevu, in the No.13 jersey.
It means Fiji's record try-scorer Vereniki Goneva, who has scored 22 times, moves to the bench.
While Fiji was well beaten 37-14 when the teams last played in 2017, the world's ninth-ranked team have since made strides, notching test wins over Italy, Scotland and a first-ever defeat of France in Paris last November.
A fearsome-looking backline is served by a pack laced with players hardened from experience in the European club top flight.
All five players who are at their third tournament are in the 23, including No.8 Viliame Mata and lock Leone Nakarawa, both rated among Europe's top forwards.
The pair also won sevens gold at the Rio Olympics, alongside Josua Tuisova, who is on the right wing.
Sydney-born Ben Volavola will be familiar to the Wallabies, having played Super Rugby for the Waratahs and Melbourne Rebels in the past.
Prop Campese Ma'afu is the younger brother of former Australian prop Salesi Ma'afu and is named after former Wallabies great David Campese following his starring role on the 1984 Grand Slam tour of Europe.