Mowen will hand the captaincy reins to veteran Stephen Moore after succumbing to an inflamed joint which is hitting a nerve in his neck.

It's the first game Mowen will miss since joining the Brumbies at the start of the Super Rugby campaign.

He said it was ''incredibly frustrating'' being on the sideline, but was adamant sitting in the stands was the best decision for his team.

The 28-year-old has only missed a handful of matches in the past four years and expects to be available for selection next week.

''It was a case of if I went out there and last just 10 minutes, then that's putting the team in the worst possible position being a man down that early,'' Mowen said.

''If I was sweet I would be playing, but I'm very confident it will be right by the end of the week.

''It's just more about giving the match-day 22 the best possible preparation, because we're well aware of the threat the Lions pose.''

The Brumbies have been in Johannesburg since Sunday. If they beat the Lions, they will ensure they remain at the top of the Australian conference before returning to play the NSW Waratahs at Canberra Stadium next week.

Mowen has been a strong leader for the Brumbies in their new generation.

But Moore is a Wallabies veteran and highly respected by every player in the competition.

Mowen said there would be minimal disruption with Moore leading the team on to the field.

Moore is a vice captain with Dan Palmer and Pat McCabe, but he is the perfect replacement to fill the void left by Mowen.

''[Moore] has a massive leadership role in the team anyway and he's always got a voice in the direction of the team,'' Mowen said.

''It's an easy transition for him to take the reins.

''We haven't taken things for granted about the way we played last week, the boys have really ripped in this week and that's what we needed.''

The Brumbies have tweaked their forward pack with Mowen absent and Dan Palmer also overcoming niggling injuries.

Irish prop Ruaidhri Murphy moves into the starting XV with Ben Alexander shifting to the tighthead side of the scrum.

Peter Kimlin gets his chance to start at blindside flanker after spending the past two weeks on the bench and Leon Power replaces Sam Carter in the second row.

Kimlin will be given the responsibility of calling the lineout plays and forwards coach Laurie Fisher said it was a chance for the 26-year-old to stand up as a leader.

''We're very confident in the depth we've got and Kimmo has given great service off the bench the last couple of weeks,'' Fisher said.

''He might not have the lineout nous that Benny has, but he will do the job.

''He's played over 50 games now and is one of our most experienced players.

''We just have to keep his head clear with what is expected. He always does a lot of good things but there are one or two errors and he understands he has to maximise the good things this week.''

Brumbies: Jesse Mogg, Henry Speight, Andrew Smith, Pat McCabe, Joe Tomane, Christian Lealiifano, Nic White, Fotu Auelua, Michael Hooper, Peter Kimlin, Leon Power, Scott Fardy, Ben Alexander, Stephen Moore (capt), Ruaidhri Murphy. Reserves: Anthony Hegarty, Scott Sio, Sam Carter, Ita Vaea, Ian Prior, Robbie Coleman, Tevita Kuridrani.