Australia captain James Horwill is out of Saturday's match against South Africa due to a hamstring injury.
Horwill sustained the injury during training on Tuesday and will now be unavailable for the Wallabies next two matches against South Africa and Argentina.
The 28-year-old Queensland Reds lock has been replaced in the starting line-up by Kane Douglas, with Ben McCalman coming onto the bench.
Scrum-half Will Genia will lead the side in Horwill's absence, with the Wallabies defeating South Africa 26-19 under Genia's leadership a year ago in Perth.
"Will is a proven leader and has had plenty of success as captain for the Queensland Reds and also for Australia," said McKenzie.
"He is a player that thrives with the added responsibility and he has always stepped up when given the opportunity to lead. I'm sure this will bring the best out of him.
"It's extremely disappointing to lose James but after discussions with medical staff we felt it was important not to risk further injury when he isn't ready.
"Scans revealed his injury was on the lower-end in terms of severity and we expect him to be back to full fitness when we embark on our two-game tour of South Africa and Argentina in a few weeks."
Australia: 15 Israel Folau, 14 Nick Cummins, 13 Adam-Ashley Cooper, 12 Christian Lealiifano, 11 James O'Connor, 10 Quade Cooper, 9 Will Genia (c), 8 Ben Mowen, 7 Michael Hooper, 6 Scott Fardy, 5 Kane Douglas, 4 Rob Simmons, 3 Sekope Kepu, 2 Stephen Moore, 1 James Slipper.
Replacements: 16 Saia Faingaa, 17 Scott Sio, 18 Ben Alexander, 19 Ben McCalman, 20 Jake Schatz, 21 Nic White, 22 Matt Toomua, 23 Jesse Mogg.
Date: September 7
Venue: Suncorp Stadium, Brisbane
Kick-off: 20:05 (10:05 GMT)
Referee: George Clancy (Ireland)
Assistant referees: Nigel Owens (Wales), Glen Jackson (New Zealand)
Television match official: Ben Skeen (New Zealand)
Assessor: Clayton Thomas