The Brumbies are refusing to give up on their championship dreams as they battle through a horror mid-season slump that has left them clinging to a play-off spot.

Moore vowed to fight for a place in the finals and said "the worst thing we could do is drop our bundle" after a shattering one-point loss to the Cape Town Stormers at the weekend.

The Brumbies have one game left on their tour of South Africa and need to beat the Johannesburg Lions to give themselves any chance of staying at the top of the Australian conference.

Somehow the Brumbies hold a one-point lead on the Australian ladder, but one defeat would almost certainly see them tumble to as low as 10th position.

"The effort is there, we have to use that as a starting point. I just want the guys to stay positive," Moore said.

"The worst thing we could do is drop out bundle and peter out for the season. If we finish strong, there's a good chance we'll make the finals.

"That's all we need to focus on. The challenge is to keep the positivity; we're still in this competition, there are plenty of teams in the same situation as us. We've got to fight to make the finals."

Brumbies playmaker Matt Toomua will join the team in Johannesburg after recovering from an ankle injury.

Coach Stephen Larkham must decide whether Christian Lealiifano retains the five-eighth duties while shifting Toomua to inside-centre.

Toomua has been the Brumbies' first-choice pivot for the past four years, but has recently established himself as the Wallabies' inside-centre.

The Brumbies' season has been punctuated by missed opportunities, which have put them in danger of missing the finals for the first time since 2012.

They have lost five games by five points or less, including their loss to the Stormers.

Lealiifano missed a relatively easy conversion attempt with 10 minutes to go, which would have lifted the Brumbies to a crucial win.

The tight loss was a reflection of the Brumbies' fortunes this year and could haunt them if they fail to secure a play-off berth.

The Brumbies maintain a staunch belief they can turn things around, rejecting any suggestion that the mid-season rut has damaged their confidence.

"I don't think it has [hit our confidence], I just don't think we've had much luck this year," flanker Scott Fardy said. "The luck has to turn eventually, and hopefully that's this week against the Lions.

"The season's definitely not gone, you can see that we're not that far off. It's going to be the tightest finals race ever and the margins are getting smaller – that makes it incredibly hard.

"We don't have to change too much, we're working in patches. But we have to fix up our discipline."

SUPER RUGBY ROUND 14

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