Rugby-Wallabies prop Ala'alatoa out of Pumas clash

SYDNEY, Sept 11 ( Reuters) - Wallabies prop Allan Ala'alatoa has been ruled out of their Rugby Championship clash with Argentina next week in Perth after sustaining a knee injury in Saturday's 23-17 victory over South Africa.

The 22-year-old ACT Brumbies prop, who made his test debut earlier this year, was wearing a knee brace at Brisbane airport on Sunday and was heading to Sydney for further treatment rather than to Perth with the rest of the team, local media reported.

Toby Smith and Tom Robertson have been called up as cover.

"It's unfortunate but it's good to have those guys ready to roll," Australian assistant coach Nathan Grey told reporters.

"He's been among a number of new guys who've come into that Wallaby set-up and really performed well.

"That's what we want from all the guys coming in is to deliver their strengths."

The Wallabies' victory ended a six-match losing streak stretching back to last year's Rugby World Cup final and released some of the pressure on coach Michael Cheika.

Australia had started 2016 with high hopes of building on their run to the World Cup final and possibly even reclaiming the Bledisloe Cup from world champions New Zealand.

A 3-0 series loss to England in June and then two successive hammerings at the hands of the All Blacks, which ensured the symbol of trans-Tasman supremacy remained in New Zealand, had led to the side being labelled the worst in a decade.

The victory over the Springboks, while far from perfect, at least showed signs of improvement against a South African side still adapting to new coach Allister Coetzee.

At times Australia looked like a side mindful they had lost their last six games and were desperate to break out of the slump.

Veteran scrumhalf Will Genia continues to be among their best players and seems to be rekindling his old Queensland Reds combination with Quade Cooper.

Cooper and Bernard Foley, who is playing at inside centre, however, still look to have issues on defence, though Cheika said he would persevere with the duo.

"I thought their partnership improved again this week. They complemented each other well," Cheika told reporters

"Bernard played a bit flatter and ran with the ball as well. He's probably been a bit deep to attack in the last couple of weeks.

"Quade, with Bernard and Willy Genia, managed the game really nicely."

(Reporting by Greg Stutchbury in Napier; Editing by Peter Rutherford)