Lealiifano has taken on extra responsibility as the Brumbies' chief playmaker during Toomua's injury-forced absence over the past month.

While most expect Toomua to slot back into flyhalf if he joins the team in Johannesburg on Monday, Larkham is considering keeping Lealiifano in the pivot role and shifting Toomua to inside centre, a position he has played in for the Wallabies.

Toomua and Lealiifano are likely to battle for Australia's No.12 jersey for this year's World Cup.

"Christian's been itching to play No.10 for a number of years … he's been very good," Larkham said.

"He's taken his opportunities, he's liking controlling the play and I think he's improved his game each week.

"It's a difficult decision with [Toomua] coming back. They both don't care what position they play, whatever is best for the team."

The Brumbies play the Cape Town Stormers in a crucial battle at Newlands on Sunday morning with their Super Rugby title hopes dangling by a thread.

Larkham has also backed goal-kickers Lealiifano and Nic White to boot their way back to form if the Stormers turn the match into a penalty duel.

Missed goal-kicking opportunities have been costly for the Brumbies this season, with three matches decided by three points or less.

White missed an after-the-siren penalty kick in his last match three weeks ago which would have given the Brumbies victory against the Auckland Blues.

Lealiifano missed a crucial penalty from in front as the Brumbies lost to the NSW Waratahs by three points last week.

"The best teams in the competition always have good goal-kickers," Larkham said. "We found that last year, Christian was a little bit off and our back-up kickers didn't do their job, that hurt us.

"But it's something you can turn around, you can come in and out of form quite easily."

Stormers sharpshooter Demetri Catrakilis has nailed his past 27 shots at goal in a row.

The Stormers have taken 10 penalty shots in their past two matches, compared to four by the Brumbies.

White is back in the starting team after missing the past three weeks with an ankle injury.

He admitted he was stung after missing the last-second penalty attempt against the Blues, but insists it won't rattle his confidence.

"It's just part of being a kicker, it would be foolish to say that it doesn't knock your confidence but I won't hesitate putting my hand up to take another one," White said.

"You back yourself to get them more times than not. It could have been a bit of a get out of jail card against the Blues, but that's the way it goes."

Lealiifano has scored 103 points this season, putting him third in the overall scoring rankings for the competition.

SUPER RUGBY ROUND 13

Sunday: Cape Town Stormers v ACT Brumbies at Newlands, 1.05am. TV time: Live on Fox Sports 2.