James Slipper has signed a two-year contract extension after turning his back on overseas interest to stay in Canberra.

It's a significant moment for Slipper, whose career was at a crossroads at the end of 2018 after he was ostracised in Queensland following positive tests to illicit drugs.

But the Wallabies veteran has got his career back on track in the capital, playing at the World Cup last and forming a devastating front-row partnership with three other international Brumbies.

Slipper and Scott Sio have shared the loosehead prop role for two seasons, teaming up with Wallabies rake Folau Faingaa and tighthead Allan Alaalatoa.

The Test quartet has given the Brumbies a destructive scrum weapon given few teams can match their international prowess.

All four have signed contract extensions, with Slipper, Sio and Faingaa committed until the end of 2022 and Alaalatoa locked in until the end of 2023.

Slipper, a 96-Test prop with 127 games of Super Rugby experience, said he had found a new home in Canberra after spending all of his rugby life in Brisbane before being told he was unwanted at the Reds.

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The former Wallabies skipper's leadership and experience has been crucial to helping the Brumbies through a transition period this season after the departure of the club's most senior players.

They have won four of five games so far and can equal their best start to a season in 16 years if they topple the NSW Waratahs at home on Sunday.

"We were a young team [when the Reds won the title in 2011] and there's quite a few young players in this team," Slipper said.

"I've always said if you're good enough, you're old enough. The good thing about the Brumbies is they've recruited some good young men and they're competing hard for spots. That's all you can ask and they keep the older blokes on their toes. That drive pushes their performance."

The Brumbies have won six of their past seven games against the Waratahs, including the past three in a row. They have also won their past seven Australian conference battles.

Another win can put the Brumbies well ahead in the Australian conference race, but they are on edge for a NSW backlash after the Waratahs were thumped by the Chiefs last weekend.

"The reality is they haven't performed very well, but we have to tread lightly around that because they can bounce back," said back-rower Tom Cusack.

"We're sitting where we want to be. It's just about making sure we stay there."

Cusack and Will Miller will have the job of trying to shut down Wallabies skipper Michael Hooper, who will be desperate to lift the struggling Waratahs.

"He's a class player, everyone knows that. He's always there and still running in the last couple of minutes. We're by no means taking him lightly. But we have to look at the bigger picture ... once you focus on an individual, you lose your mind set on the whole game. This is going to be a test to see where we are this season."