SYDNEY, Sept 4 (Reuters) - The headlines have focused on Bryan Habana's 100th test and a new Wallabies halfback partnership but it is in the maelstrom of the forward battle that Saturday's clash between Australia and South Africa is likely to be decided.
The Springboks go into the match at Perth's Subiaco Oval (1005 GMT) leading the Rugby Championship after two narrow victories over Argentina, while Australia remain winless after a draw and a 51-20 pummeling at the hands of the All Blacks.
McKenzie responded to the humiliation at Eden Park by reshuffling his backline but the six-two split in favour of the forwards on his replacements bench is perhaps a better indication of the sort of match he is expecting.
Scrumhalf Nick Phipps and flyhalf Bernard Foley, the fulcrum of New South Wales Waratahs' Super Rugby triumph, will start a test together for the first time after McKenzie abandoned his experiment with Kurtley Beale at number 10.
It will be the performance up front, however, that is likely to determine whether Australia can secure a first victory against one of the traditional southern hemisphere powers since McKenzie took charge.
If McKenzie had any doubt about South Africa's approach to the match, they were dispelled when Heyneke Meyer made six changes to the team that squeaked past Argentina 33-31 in Salta.
Adriaan Strauss came in at hooker alongside Tendai "The Beast" Mtawarira in the front row, Victor Matfield slotted back into the second row and Morne Steyn returned at flyhalf in place of the dropped Handre Pollard.
Strauss wins his place ahead of Bismarck du Plessis because of his discipline, strong scrummaging and accurate throwing-in, while Matfield remains an almost peerless ball winner at line-out time.
With Steyn's booming boot ready to target the corners and punish any Australian indiscipline within 50 metres of their line, South Africa look set up to monster their opponents at the set-piece and maul them into submission or penalties.
Despite the hammering the Australia pack took in Auckland, McKenzie made only one enforced change to his forwards with James Hanson, his fourth choice at hooker, replacing the injured Nathan Charles.
Australia will be looking for one of the increasingly frequent "good days in the office" at set piece and hope to get the upper hand in the back row battle for breakdown supremacy against a less experienced Springbok loose trio.
Captain Michael Hooper can be expected to be as tireless as ever at openside, while the abrasive Scott Fardy at blindside and number eight Wycliff Palu need big games to be sure of retaining their starting spots.
Palu especially needs to show the sort of form with ball in hand that he did in the French series earlier this year and in that quest the selection of his Super Rugby team mate Phipps could be a big help.
The lively Phipps presents a greater threat than the demoted Nic White around the fringes and has shown great aptitude for getting his big ball carriers moving over the gainline.
Strauss's selection means the fiery Du Plessis will be rested when the benches are cleared for the last 20 minutes, while loose forward Warren Whiteley will also be champing at the bit to get on the field and win his first cap.
McKenzie has offered former skipper James Horwill a chance to revive his career off the bench but Australians hope he is not left regretting the absence of Will Skelton if a Springbok maul is rolling towards the try line with seconds to go.
Australia: 15-Israel Folau, 14-Adam Ashley-Cooper, 13-Tevita Kuridrani, 12-Matt Toomua, 11-Rob Horne, 10-Bernard Foley, 9-Nick Phipps, 8-Wycliff Palu, 7-Michael Hooper (captain), 6-Scott Fardy, 5-Rob Simmons, 4-Sam Carter, 3-Sekope Kepu, 2-James Hanson, 1-James Slipper
Replacements: 16-Saia Faingaa, 17-Pek Cowan, 18-Ben Alexander, 19-James Horwill, 20-Scott Higginbotham, 21-Matt Hodgson, 22-Nic White, 23-Kurtley Beale
South Africa: 15-Willie le Roux; 14-Cornal Hendricks, 13-Jan Serfontein, 12-Jean de Villiers (captain), 11-Bryan Habana, 10-Morne Steyn, 9-Ruan Pienaar, 8-Duane Vermeulen, 7-Marcell Coetzee, 6-Francois Louw, 5-Victor Matfield, 4-Eben Etzebeth, 3-Jannie du Plessis, 2-Adriaan Strauss, 1-Tendai Mtawarira
Replacements: 16-Bismarck du Plessis, 17-Trevor Nyakane, 18-Marcel van der Merwe, 19-Lood de Jager, 20-Warren Whiteley, 21-Francois Hougaard, 22-Pat Lambie, 23-Lwazi Mvovo
Referee: George Clancy (Ireland) (Editing by Ian Ransom)