The Brumbies lost the penalty count 11-5 in their loss to the Stormers, with the home side running away with a 31-11 win at the death to inflict the Brumbies' first loss of the Super Rugby season.

In four games this year the Brumbies have been hit with three yellow cards and one red card, effectively limiting them to 14 men for 47 of the 320 minutes they've played so far.

Some decisions by referee Jaco Peyper left the Brumbies baffled at times, including his call to award a try to Dillyn Leyds in the dying minutes despite replays appearing to show Leyds dropped the ball.

But Brumbies co-captain Stephen Moore says discipline must improve ahead of a crucial clash against the Free State Cheetahs in Bloemfontein on the weekend.

Rather than put the blowtorch on the officials, Moore said the Brumbies have to take ownership of the loss and learn to be better.

Brumbies hooker Josh Mann-Rea was sent off for lashing out at Stormers prop Oli Kebble and he now faces suspension as the Super Rugby judiciary considers the case.

Mann-Rea's brain snap was a major incident, but it was the little moments that hurt the Brumbies most. They conceded seven penalties in the first 40 minutes.

"We've got to own the loss now and move on ... The Stormers were the better team on the night, they were desperate and they deserved to win," Moore said.

"It makes next week a very important game for us. Maybe our discipline was a little bit off, we gave away penalties within kicking distance and we knew they would use that to get into the game.

"You're constantly looking at how you can improve, that's one of the challenges of the season. There's a lot of talk about the officiating, but we can't control any of that.

"Our discipline is something we're constantly looking at and I think every team is. It's an area where you don't want to let teams in and there were a couple of incidents that probably let us down. In the entirety of the game that adds up."

The Brumbies were strangled out of the contest at Newlands as the Stormers used their tactical kicking to their advantage.

The Brumbies were never out of the match, but when Mann-Rea was sent off in the 63rd minute the tide turned.

In an indication of the Stormers' possession dominance, they won 18 lineouts compared to the Brumbies' five and stole the ball on three separate occasions from a Brumbies throw.

The Brumbies went into the game having won their first three matches, but they hit a Stormers brick wall and struggled to bust through in their first game in South Africa.

The loss makes the clash against the Cheetahs even more important, with the Brumbies desperate to regain their winning momentum before returning to Canberra.

"It's a massive game against the Cheetahs, we'll put all of our focus into that now," said coach Stephen Larkham.

"We'll start nice and fresh and be ready to get into them. The guys put a lot of effort into the game [against the Stormers] and it just sort of slipped away from us. Everyone is quite disappointed, but keen to get back into that routine."

CAPE TOWN STORMERS 31 (Siya Kolisi, Dillyn Leyds, Vincent Koch tries; Kurt Coleman 3 penalties; Kurt Coleman; Jean-Luc du Plessis conversions) bt ACT BRUMBIES 11 (Tevita Kuridrani try; Christian Lealiifano 2 penalties) at Newlands, Cape Town on Sunday morning (AEDT). Referee: Jaco Peyper.