Three uncapped Wallabies for Boks
Queensland Reds lock Lukhan Tui, Western Force back Billy Meakes and Reds outside back Izaia Perese will be vying for their Wallabies debut over the next fortnight.
Reds flank Adam Korczyk was dropped from the original squad, with Cheika preferring a slightly smaller touring party for the games in Bloemfontein and Mendoza.
The Wallabies depart for Johannesburg on Saturday as they aim to go one better against the Springboks in Bloemfontein following a 23-all draw in Perth a fortnight ago.
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Australia last played in Bloemfontein in 2010, when they snatched a last-gasp 41-39 win through a long-range penalty kick from Kurtley Beale after the full-time siren.
The Wallabies also won on their last visit to Mendoza back in July 2015, after 14 points from the boot of Bernard Foley secured a 34-9 win.
Players currently unavailable due to injury include James Slipper (Achilles), Sefa Naivalu (ankle), Dane Haylett-Petty (arm) and Jermaine Ainsley (foot).
The Wallabies face the Springboks on September 30 and Argentina on October 7.
Australia:
Forwards: Allan Alaalatoa, Rory Arnold, Adam Coleman, Jack Dempsey, Tetera Faulkner, Ned Hanigan, Michael Hooper (captain), Sekope Kepu, Sean McMahon, Stephen Moore, Tatafu Polota-Nau, Tom Robertson, Izack Rodda, Rob Simmons, Scott Sio, Lopeti Timani, Lukhan Tui, Jordan Uelese.
Backs: Kurtley Beale, Israel Folau, Bernard Foley, Will Genia, Reece Hodge, Samu Kerevi, Marika Koroibete, Tevita Kuridrani, Billy Meakes, Izaia Perese, Nick Phipps, Joe Powell, Curtis Rona, Henry Speight.
