Slipper demotion a tough call: Cheika

The decision to drop Australia's most experienced prop against scrum specialists Argentina was not made lightly, according to coach Michael Cheika.

The 82-Test veteran James Slipper on Thursday lost his place in the match day 23 to a pair of rising stars of the Australian scrum family, Allan Alaalatoa and Tom Robertson.

It's potentially a risky play by the wily Cheika, with Argentina renowned for their set piece strength and technical prowess at scrum time.

But, while admitting it was tough to omit a player he freely calls a friend both inside and outside Camp Wallaby, he insists Slipper's standards have dipped and his hand was forced at the selection table.

The 27-year-old has become a repeat offender in giving away scrum penalties recently, including conceding a crucial one late in last week's 18-10 loss to South Africa.

"It's definitely a tough call for James," Cheika said.

"I think we are really trying to be diligent in rebuilding the team about the discipline to detail in everyone's role.

"Other players so far have missed out because of that, and I think in discussing with James he needs to improve certain parts of his game, that I feel aren't up to the standard that he has.

"He has a high standard. He's one of our most capped players and I want him to go beyond those standards that he's set himself in the past."

Slipper's demotion will give added responsibility to Robertson, who takes over as the team's bench loosehead prop - having spent the season playing tighthead for the Waratahs.

It's a role Cheika believes the 22-year-old is well-equipped to handle - someone who can flip between either position.

"We see that he's a player who can fulfil that role and we're going to start working on him for that," Cheika said.

Robertson started the season as on an emerging player contract with the Waratahs, but is quickly emerging as an excellent prospect under Cheika.

"I don't think Tom Robertson imagined he's going to be playing in front of James Slipper at the start of this season," Cheika said.