The childhood friends hope beating the Waratahs will cap off a massive double signing coup, with both committing to three-year extensions to stay with the Brumbies until at least the 2019 World Cup.

It comes 25 years after their dads - David Sio and Vili Alaalatoa - were part of a gallant Samoan team at the 1991 World Cup.

The Brumbies' front-row duo hope they can follow the same path to become Test teammates in the coming years.

But the number one priority is reversing the trend against the Waratahs at Canberra Stadium on Friday night to end almost two years of misery against the Brumbies' arch rival.

The Brumbies have sold more than 15,000 tickets for the match, with the club to donate $20,000 to the Domestic Violence Crisis Service if they get a crowd of 20,000.

"You don't win unless you win the physical battle and that's something we're looking to rectify," Sio said.

"We have to come together as a group, draw a line in the sand, and say 'enough is enough' and really step up to it. That starts tomorrow.

"I believe we've done the groundwork this week ... you've got to take the mental approach into the game where you're level headed and not looking at it from an emotional point of view.

"It's the calm before the storm. Hopefully we put it into good effect [on Friday night]."

Sio and Alaalatoa will work as a loosehead prop tag team, with Sio being recalled to the starting side for the second game of the season.

The pair share a family bond and a rugby history that has brought them closer together.

That was reflected in their new contract announcements less than 48 hours apart, with Alaalatoa trying to forge his career to join Sio in the Wallabies pack.

Brumbies coach Stephen Larkham described the pair as a "cornerstone" for the club's forward stocks as he now turns his attention to re-signing a host of other stars.

David Pocock is still in negotiations as he weighs up a 12-month sabbatical while Jarrad Butler, Ben Alexander and Tom Staniforth are all off contract.

Sio says he has unfinished business in Super Rugby and in the Test arena as he sets his sights on adding to his 16 Wallabies caps.

"I'm really happy with Australian rugby and how we went last year, I just really wanted to be a part of it," Sio said.

"They've shown a lot of faith in me and it comes down to me being able to repay that over the next three years. I believe in my ability and that I can.

"There's so much I want to achieve at higher honours but to do that you've got to do well at Super Rugby. I've given a lot to the Brumbies and they've given a lot to me, that's in my mind."

Sio and Alaalatoa are competing for starting spots this season. Alaalatoa got the No. 1 jersey for round one, but Sio has snatched it back for the Waratahs derby.

"Allan has come along leaps and bounds, he fully deserved his start last week and that's great for me - it adds that fire and competition," Sio said.

"That's what you want, you never want an easy ride and that's what Allan is doing, he's pushing me and growing as a player.

"Growing up I thought myself and my brother [Pat] would play together, but I've realised that your rugby journey is your own. You've just got to do what you can with whatever opportunity you get. For now, me and Allan will enjoy our time in Canberra."

Sio was one of two changes to the Brumbies' starting side, with Blake Enever replacing Rory Arnold at lock.

SUPER RUGBY ROUND TWO

Friday: ACT Brumbies v NSW Waratahs at Canberra Stadium, 7.45pm. Tickets available from Ticketek. Curtain-raiser: Brumbies Colts v Next Gen Blues in Super under-20s at 5.15pm.

Brumbies team: 15. Aidan Toua, 14. Henry Speight, 13. Tevita Kuridrani, 12. Matt Toomua, 11. Joseph Tomane, 10. Christian Lealiifano, 9. Tomas Cubelli, 8. Ita Vaea, 7. David Pocock, 6. Scott Fardy, 5. Sam Carter, 4. Blake Enever, 3. Ben Alexander, 2. Stephen Moore, 1. Scott Sio. Reserves: 16. Josh Mann-Rea, 17. Allan Alaalatoa, 18. Les Leuluailii-Makin, 19. Jordan Smiler, 20. Jarrad Butler, 21. Michael Dowsett, 22. Nigel Ah Wong, 23. Andrew Smith.

Waratahs team: 15. Israel Folau, 14. Matt Carraro, 13. Rob Horne, 12. David Horwitz, 11. Zac Guildford, 10. Kurtley Beale, 9. Nick Phipps, 8. Jed Holloway, 7. Michael Hooper, 6. David Dennis, 5. Will Skelton, 4. Dean Mumm, 3. Angus Taavao, 2. Tatafu Polota-Nau, 1. Paddy Ryan. Reserves: 16. Tolu Latu, 17. Matt Sandell, 18. Jeremy Tilse, 19. Sam Lousi, 20. Wycliff Palu, 21. Jack Dempsey, 22. Matt Lucas, 23. Bryce Hegarty.