Brumbies coach Dan McKellar has made four changes to his starting XV, with Wallabies duo Pete Samu and Henry Speight returning alongside Tom Cusack and Toni Pulu.

The only stronger side McKellar could have named would include David Pocock, but a recurring calf injury forced the star flanker's Super Rugby retirement last month.

McKellar said he was forced to make some tough selection calls this week but emphasised that's why the Brumbies are title contenders in 2019.

"If you're seriously going to give the competition a shake you need to be in that position. There's guys playing good footy who unfortunately aren't in the 23," McKellar said.

"But it's a good position to be in. I remember (former coach) Steve Larkham always talking about 2004 (the Brumbies most recent title) and the minimal players they used that year.

"You've got to have a bit of luck to win any competition and to win finals games there's an element of it too but also hard work.

""The guys coming back in have performed really this season and got us to this point, so it would have been a pretty harsh call to say boys you're not in the 23 this week."

The Brumbies enter in the clash in red-hot form by winning eight of their past nine games, and they are gunning for seven straight wins for the first time in club history against a team they didn't face in the regular season.

The Durban outfit kept their season alive with an after-the-siren try against the Stormers last week and travel to Canberra as underdogs.

McKellar said he's wary of the Sharks' dangers but remains confident his men can justify their favourites tag.

"When you get to this stage of the season the opposition is always going to be quality, and they're a dangerous side with threats across the park and a game that can win finals footy," McKellar said.

"They're the only team that has come out of Christchurch with points for a long time. In a one-off game they're going to be dangerous.

"They're a typical South African side with big men and a good set-piece and speed on the edges. We're well aware of their threats but we'll continue to focus on us.

"We just have to play our game well. If we start worrying about outcomes now we'll get ourselves into trouble.

"It's a finals game with a bigger crowd and a lot more interest which is great, and you've got to embrace that but also don't get too far ahead of what's important.

"It's about being excited but not letting emotion and finals fever get the better of you."

Brumbies: Tom Banks, Henry Speight, Tevita Kuridrani, Irae Simone, Toni Pulu, Christian Lealiifano (capt), Joe Powell, Pete Samu, Tom Cusack, Rob Valetini, Sam Carter, Rory Arnold, Scott Sio, Folau Faingaa, Allan Alaalatoa. Res: Connal McInnerney, James Slipper, Les Makin, Darcy Swain, Lachy McCaffrey, Jahrome Brown, Matt Lucas, Tom Wright.

Australian Associated Press