The Brumbies can make a major statement in Canberra next weekend when they play the NSW Waratahs in a derby battle.

They have won four of five games so far this season - their best start since 2016 - while the Waratahs are languishing after being smashed by the Waikato Chiefs on Friday.

The Brumbies' rise has come as a surprise to many given they lost Christian Lealiifano, David Pocock, Henry Speight, Sam Carter and Rory Arnold in the off season.

But the next gen have stepped up and they're using former Brumbies skipper Gregan's advice as the motivation for their charge.

Gregan and Justin Harrison were invited into the Brumbies' inner sanctum earlier this year as part of the club's 25th season celebrations. Gregan, a World Cup-winner and two-time Super Rugby champion, told the unheralded Brumbies to seize their opportunities.

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"Super Rugby clubs win because of their depth and consistency," Gregan told The Sunday Canberra Times.

"You need a bit of luck along the way, but you have to call on different players and different times and you need to be ready to go.

"The Brumbies are doing that, you can see that in the way they're playing. They're changing players, guys are coming off the bench and everyone's contributing.

"It doesn't matter if you're starting or finishing, the team is still functioning.

"I guess it is rebuilding this year, but there are still a lot of quality players. That's the nature of rugby ... and what you've seen is young players coming in and wanting to play at that next level.

"When you've got the quality the Brumbies have got, there's no need to rebuild. You just bring the next players along."

The Brumbies have 12 players who are in either the first or second season of Super Rugby and some are becoming major contributors.

Ryan Lonergan and Noah Lolesio became the third youngest starting halves combination in Brumbies history in the team's win against the Japan Sunwolves.

Teenager Reesjan Pasitoa, who is the second youngest player to debut in Brumbies history, came on in the second half of the same game to earn his second cap.

Tom Ross is the back-up tighthead to captain Allan Alaalatoa, Lachlan Lonergan has helped filled the void of Folau Faingaa and NRL converts Tom Wright and Solomone Kata have quickly found their feet in rugby union.

"We're not in that transition phase any more," said former junior Wallabies front-rower Ross. "We've really got to up the ante and start pushing for spots because we're not going to be looked at as kids.

"It's good to get the debuts out of the way, but now the real fun starts.

"George Gregan came and spoke to us in Newcastle for our pre-season. His his key message was when your opportunity comes, you have to be ready."

Lonergan, who made his starting debut against the Sunwolves, added: "It's time to step up now and really take that on our shoulders. The sooner the better.

"I think we're all good enough to do it, it's just getting your head around it and then doing it."

The Brumbies are unbeaten in three Australian conference battles this season, beating the Queensland Reds, Melbourne Rebels and the Sunwolves.

They will be heavy favourites to topple the Waratahs, who are struggling with just one win so far this year.

But taking their arch rivals lightly would be a major mistake in a week that generally brings out the best in both teams.

The Waratahs will have bruised egos after flopping against the Chiefs, conceding 51 points in Wollongong.

Faingaa could come back into the team after being given extra time to recover from an ongoing toe issue, while McKellar will be mulling other selection decisions.

Toni Pulu injured his shoulder after scoring a try against the Sunwolves and will be assessed early in the week to dermine his availability, while Wright, Kata, Andy Muirhead and Mack Hansen are also battling for wing spots.