Australia's clash against Samoa at the new Parramatta Stadium next weekend is a chance for Allan to get some younger sibling revenge.

"If I see him at the bottom of a ruck, I'm definitely going for the cheap shot," Allan grins.

"He got me plenty of times when we were younger and he got me in Super Rugby this year, so there's a bit of extra motivation for me.

"It's a pretty proud moment for our family. To be able to represent both countries, it's something our whole family is proud of. Everyone will be there ... I can't wait."

The Wallabies will return to Australia this week after spending 10 days in Noumea for a fitness camp in the hope it will help them break a 20-year World Cup drought.

Teenage sensation Jordan Pataia has already been ruled out of the showdown with Samoa, but David Pocock is expected to play his first game since March in what would be a massive boost for Australia's chances.

The game will be an important testing ground for coach Michael Cheika, who will use the contest as the last opportunity to test combinations and players.

But there's special incentive for the Wallabies' Samoan connection of Allan Alaalatoa, Scott Sio, Christian Lealiifano, Matt Toomua, Jordan Uelese and Lukhan Salakaia-Loto.

Lealiifano almost committed to Samoa's World Cup campaign 12 months ago after fearing his Wallabies hopes had evaporated.

Uelese is a 'chief' in his father's village of Aufaga and Sio's dad David played alongside Vili Alaalatoa in Samoa's 1991 World Cup side.

MORE RUGBY

Now front-row brothers Allan and Mike will go head to head for the next step of their shared World Cup dream, albeit as they walk different paths for different countries.

ACT Brumbies tighthead prop Allan has become an anchor for the Wallabies' scrum and will make his World Cup debut in Japan this month.

Mike has carved out his career in New Zealand after being shunned by the NSW Waratahs, winning three Super Rugby titles with the Canterbury Crusaders before pledging his allegiance to Samoa.

The brothers are used to trading blows after a childhood of boxing sessions and rugby training, followed by separate careers as professional players.

Allan has never beaten Mike in Super Rugby battles, but mum Emma made sure both sides were supported by knitting a "Team Alaalatoa" crest for their Brumbies-Crusaders duels.

"I ran straight at him in the last game we played [against each other] in Christchurch and he dragged me back a bit," Allan said.

"But he was assisted by someone else so I'd never give him that one. Being the younger brother you're always trying to pester him and as soon as we cross the white line I'm continuing that.

"If I can get a shot on him it's definitely something I want to go for ... But really we're just grateful for the opportunities we've got.

"I think the whole family is going to be split but it's going to definitely be a proud moment if we both get the nod to play that game and represent both of our countries."

Rugby Australia is hoping a bumper crowd will pack into the stands at Parramatta, just a 20 minute drive from the Alaalatoa family home.

"Mum and dad were pretty emotional when I told them I'd been picked [for the World Cup]," Allan said.

"Phil Kearns called me to tell me I was in. It was a phone call I've been dreaming of, it was a huge moment for me.

"To be able to do something that my dad did, and then have Mike for Samoa as well, it's just such an amazing opportunity for our family."

WORLD CUP FAREWELL

Saturday: WAllabies v Samoa at Parramatta Stadium, 7.30pm.