But lock Sam Carter says they won't turn away from the success of their rolling maul, despite the back line being deprived of opportunities to score.

The Brumbies will play the Johannesburg Lions at Ellis Park on Sunday, needing to win to hold on to their Australian conference lead.

The Brumbies boast the best defence in the competition, conceding just 12 tries in 12 matches this year. But they've lost five games by five points or less and Carter said it's now or never to start their championship run.

"It's the pointy end of the season and we've seen teams come into form. The Canterbury Crusaders tend to do it every year," Carter said. "We know that if we stick to what we do best, we can be a real threat towards the end of the year."

The competition for Wallabies selection will add spice to a tight Australian conference finals race.

The Brumbies, NSW Waratahs and Melbourne Rebels are battling for one guaranteed spot in the play-offs.

Carter made his Test debut last year and was one of the first-choice second-rowers for the spring tour of Europe.

However, teammate Rory Arnold, Western Force rising star Adam Coleman and established players Will Skelton, James Horwill and Rob Simmons threaten to take his position.

The Brumbies have put talk of Wallabies selection on hold to ensure their focus remains on their Super Rugby campaign.

The Brumbies have lost four of their past five games and are in danger of losing three matches in a row for the first time since 2011.

"It's going to be a tough run home from here, there needs to be a few things going our way," Carter said.

"[Wallabies coach] Michael Cheika has a mind set for what he wants out of his forwards and I have to work towards that. But if I'm in form for the Brumbies then I'll put my hand up."

Brumbies flanker David Pocock has scored four tries in four weeks, all off the back of rolling mauls.

The Brumbies' lineout is statistically the best in Super Rugby, but it comes at a cost with wingers Henry Speight and Joseph Tomane touching the ball just seven times between them in 80 minutes last week.

Carter said a fear of becoming one dimensional was driving the Brumbies to search for new attacking platforms.

"The rolling maul is a big part of our game, we use it a lot to set up our plays and most of our attack off penalties," Carter said.

"It's been paying off in parts. Obviously teams will target us there to nullify it and get the competitive advantage.

"We like to keep the variation in our game so we're not a one-trick pony. We want it solid so we can go to it, but we use it to play a different way as well."

SUPER RUGBY ROUND 14

Sunday: Johannesburg Lions v ACT Brumbies at Ellis Park, 1.05am Australian time. TV time: Live on Fox Sports 2

Brumbies team: 15. Jesse Mogg, 14. Henry Speight, 13. Tevita Kuridrani, 12. Matt Toomua, 11. Joseph Tomane, 10. Christian Lealiifano, 9. Nic White, 8. Ita Vaea, 7. David Pocock, 6. Scott Fardy, 5. Rory Arnold, 4. Sam Carter, 3. Ben Alexander, 2. Stephen Moore, 1. Allan Alaalatoa. Reserves: Josh Mann-Rea, Jean-Pierre Smith, Ruan Smith, Jordan Smiler, Jarrad Butler, Blake Enever, Michael Dowsett, Robbie Coleman, James Dargaville, Nigel Ah Wong (two to be omitted).