Christian Leali'ifano, who scored the most points for the Wallabies at the 2019 World Cup, will start as Samoa's five-eighth in their opening Rugby World Cup clash with Chile in Bordeaux.
The 35-year-old, who survived cancer to return to playing elite rugby, transferred his allegiance this year to Samoa from Australia after 26 Tests.
He took advantage of a relaxation in World Rugby's eligibility rules, which means players who stand down for three years from appearing for one country can then play for another for which they qualify.
Leali'ifano played for 11 years with the Brumbies, amassing 150 caps, but most recently has turned out for Moana Pasifika in the Super Rugby Pacific competition.
Under the eligibility laws former All Blacks Steven Luatua, who starts at No.8, and the versatile Lima Sopoaga as a replacement back have also switched to Samoa.
Prop Paul Alo-Emile, who won 50 caps with the Melbourne Rebels and is a former Australian under 20s representative, has been named on the bench for Saturday's match (Sunday AEST).
The team is captained by Michael Alaalatoa, the brother of Wallabies prop Allan Alaalatoa, who is missing from the Australian squad after rupturing an Achilles.
Samoa will target Chile as their most winnable game in a pool also containing England, Argentina and Japan as they look to progress from the pool stage for the first time since 1999.
Chile lost to Japan 42-12 but put up a courageous showing in their opening match, as coach Pablo Lemoine makes four changes.
James Lay, Seilala Lam, Michael Alaalatoa (c), Chris Vui, Theo McFarland, Taleni Junior Agaese Seu, Fritz Lee, Steven Luatua, Jonathan Taumateine, Christian Leali'ifano, Nigel Ah-Wong, Tumua Manu, Ulupano Junior Seuteni, Danny Toala, Duncan Paia'aua. Res: Sama Malolo, Jordan Lay, Paul Alo-Emile, Sam Slade, Sa Jordan Taufua, Ereatara Enari, Lima Sopoaga, Ed Fidow.