Wallabies selectors should judge Christian Lealiifano on his impressive start to the Super Rugby season and not on his one-on-one battle with Berrick Barnes tomorrow night, ACT Brumbies coach Jake White says.

Lealiifano has put himself in contention for Test selection after leading the Brumbies to the top of the Australian conference after nine Super Rugby games, but faces a potential road-block tomorrow night against Barnes, a proven Wallabies flyhalf. The Brumbies have scored 16 tries in their past three matches and Lealiifano has been instrumental in the attacking onslaught.

Lealiifano started the season at inside centre, but made a permanent move to flyhalf when Matt Toomua ruptured his anterior cruciate ligament at Canberra Stadium in March.

His form has convinced White that the 24-year-old playmaker is ready to step up to the Test rugby arena.

''I'd like to believe what Christian has shown in the past couple of weeks is not going to get judged on one Saturday against Berrick Barnes,'' White said.

''Anyone who has watched him the whole season knows that [he's in good form] and I'd like to believe he won't get judged on one performance.

''He just has to keep doing what he's been doing and if he focuses on those things, everything will fall into place.''

The Brumbies have named the same back line for the third consecutive match.

While their back line is beginning to fire, constant injuries have forced the Waratahs to re-shuffle and they're still trying to their combinations.

Former Brumby Adam Ashley-Cooper has been named at fullback again and will pose a constant threat when the Waratahs attack. Barnes has moved to flyhalf after beginning the season at inside centre.

But Brumbies and Wallabies inside centre Pat McCabe expected the Waratahs back line to finally click in defence and attack.

''We've seen what they did last week [against the Crusaders] … if they defend with the same formation they'll be a lot better for the run,'' McCabe said.

''With combinations the first week is by far the hardest in getting an understanding of what guys do and getting comfortable each other. But if we run the plays we want to, hopefully we'll have some success.''

The Brumbies haven't beaten the Waratahs since 2009 and McCabe - yet to record a victory over NSW - said there was an ''extra edge'' and hype around the interstate match.