Powerful flanker Sean McMahon will replace Michael Hooper in Australia's side to take on Wales at Twickenham on Saturday in the Pool A decider.
Head coach Michael Cheika has made three changes to the XV that defeated England 33-13.
McMahon steps in at number seven for the suspended Hooper and Drew Mitchell replaces the injured Rob Horne on the left wing. Dean Mumm takes over from Rob Simmons in the second-row.
In each of their previous two team selections, the Wallabies made 14 changes compared to their most recent starting line-up.
At an average age of 28 years and 130 days, this will be the third oldest starting line-up for the Wallabies in a World Cup match and their oldest since Australia set their team record at 28 years 163 days in their 24-9 victory against Wales on 23 October 1999.
With his 111th test appearance, Adam Ashley-Cooper moves up to joint-third in the list of most-capped Wallabies, level with George Smith, and now only has George Gregan (139) and Nathan Sharpe (116) ahead of him.
Drew Mitchell's 12 career World Cup tries are the most ever by a Wallaby and rank him fourth all-time. Jonah Lomu (NZL) and Bryan Habana (RSA) share the record of 15 and Doug Howlett (NZL) is third with 13 RWC tries.
Scott Sio will make his fourth start at Rugby World Cup 2015.
Australia: 15 Israel Folau, 14 Adam Ashley-Cooper, 13 Tevita Kuridrani, 12 Matt Giteau, 11 Drew Mitchell, 10 Bernard Foley, 9 Will Genia, 8 David Pocock, 7 Sean McMahon, 6 Scott Fardy, 5 Dean Mumm, 4 Kane Douglas, 3 Sekope Kepu, 2 Stephen Moore (c) 1 Scott Sio.
Replacements: 16 Tatafu Polota-Nau, 17 James Slipper, 18 Greg Holmes, 19 Rob Simmons, 20 Ben McCalman, 21 Nick Phipps, 22 Matt Toomua, 23 Kurtley Beale.
Date: Saturday, October 11
Kick-off: 16:45 local
Referee: Craig Joubert (South Africa)
Assistant referees: Jérôme Garcès (France), Stuart Berry (South Africa)
Television match official: Shaun Veldsman (South Africa)