* Palu, White, Lealiifano among players axed
* Lock Arnold, winger Naiyaravoro only uncapped players (Adds details, quotes)
By Ian Ransom
MELBOURNE, July 10 (Reuters) - Wallabies coach Michael Cheika has omitted scrumhalf Nic White and seasoned number eight Wycliff Palu from a 31-man squad for Australia's opening match of the southern hemisphere Rugby Championship against South Africa.
ACT Brumbies back Christian Lealiifano was a third high-profile omission after the initial squad was shaved down from 40 following a training camp on the Sunshine Coast this week.
The uncapped pair of ACT Brumbies lock Arnold and New South Wales winger Taqele Naiyaravoro were retained in the squad announced on Friday, as were France-based backs Matt Giteau and Drew Mitchell.
Lock Kane Douglas, who has requested a release from Irish side Leinster and is being hotly pursued by the Australian Rugby Union with the World Cup in mind, was omitted from the Stephen Moore-captained squad.
"There were obviously some really tough calls to make," Cheika said in a statement.
"The players who have not been named in this 31-man squad will still remain part of the group and will continue to contribute. We have also taken the opportunity to rest players, as we know it is going to be a long international season.
"I have had a good chance to test some combinations and see some players in a high intensity environment. It's given me great confidence knowing we're establishing some depth in key positions."
With Brumbies halfback White out, Waratah Nic Phipps will vie with Queensland Red Will Genia for the number nine shirt for the July 18 match against the Springboks in Brisbane.
Ben McCalman and Scott Higginbotham are likely to battle for the number eight position, though 54-cap Palu may be recalled later in the series.
The other players to miss out from the initial 40 were Dave Dennis, James Hanson, Tetera Faulkner, Samu Kerevi and Toby Smith.
The Springboks opener in the abridged Rugby Championship, which also includes Argentina and New Zealand, marks the start of Australia's final warmups for the World Cup in England.
Squad:
Forwards - James Slipper, Scott Sio, Sekope Kepu, Stephen Moore (captain), Tatafu Polota-Nau, Rob Simmons, Will Skelton, Rory Arnold, James Horwill, Dean Mumm, Scott Fardy, Scott Higginbotham, Ben McCalman, Sean McMahon, Michael Hooper, David Pocock, Greg Holmes
Backs - Nick Phipps, Will Genia, Bernard Foley, Quade Cooper, Matt Toomua, Matt Giteau, Kurtley Beale, Tevita Kuridrani, Adam Ashley-Cooper, Drew Mitchell, Rob Horne, Joe Tomane, Taqele Naiyaravoro, Israel Folau.