His decision to sign a one-year contract extension is a crucial boost for the Super Rugby province just days before a must-win clash against the Pretoria Bulls at Canberra Stadium on Friday night.

Alexander backed the Australian Rugby Union's decision to allow some overseas-based players to be eligible for the Wallabies, but he said the time wasn't right to take advantage of it.

With 72 international caps, the 30-year-old is one of only a few Wallabies who the ARU will allow to play overseas and still be able to play for Australia.

But he didn't even consider chasing lucrative offers to play overseas before re-signing on Wednesday to stay with the Super Rugby province until the end of next year.

He joins a growing number of crucial Brumbies who have decided to remain in the nation's capital this season, with fellow Wallabies Sam Carter, Scott Fardy, Tevita Kuridrani and Josh Mann-Rea also opting to remain with coach Stephen Larkham.

Robbie Coleman, Ita Vaea and Rory Arnold have also recommitted, but Wallabies scrum-half Nic White, fullback Jesse Mogg and Jordan Smiler will join the French revolution at the end of the season.

Alexander said the Brumbies culture was so strong even those leaving did so with a "heavy heart".

His decision to stay means he could become the first prop to play 100 Tests for the Wallabies and do it as a Brumbies player.

He made his debut for both province and country in 2008 and has 112 Super Rugby caps.

It took until the 2013 season for him to taste Super Rugby finals action and now he's desperate to win the title.

"To go so close the last couple of years to winning some silverware, that's something that burns with me," Alexander told Fairfax Media. "Also at a national level I haven't won any silverware. I'm not ready to move on and close those chapters.

"I feel this group is going in the right direction and I want to be a part of it.

"I think the ARU have made the smart decision to try and increase the number of players that are up for selection for the national side, but for I feel for me if I want to play for the Wallabies I need to be here playing well so [Wallabies coach Michael Cheika] can see."

While Alexander is confident the Brumbies can earn a home semi-final, he said they needed to win all three games to finish in the top six.

He said their three remaining games – the Bulls at home, the Western Force in Perth and then the Canterbury Crusaders at home – were all tough.

Not only will they decide the Brumbies' finals fate, but they will also help decide whether Alexander plays at his second World Cup.

"There's seven sides in the running for five spots [after the ladder-leading Wellington Hurricanes]. We don't just want to be part of the finals, we want to go right through and you need to make sure you get a home semi and minimise your travel," Alexander said.

SUPER RUGBY ROUND 16

Friday: ACT Brumbies v Pretoria Bulls at Canberra Stadium, 7.40pm. Tickets available from Ticketek.