The Brumbies added the Melbourne Rebels' scalp to their growing collection with a clinical 30-13 win in their Super Rugby clash at AAMI Park.

After accounting for Queensland in the opening round, the Brumbies delivered an emphatic second-half performance to stamp themselves as the Australian conference heavyweights.

The Rebels led 13-12 at half-time but they were starved of ball in the second stanza and injuries to their attacking maestros James O'Connor and Kurtley Beale cruelled their chances as the Brumbies piled on 18 unanswered points.

O'Connor was steamrolled by veteran Brumbies winger Clyde Rathbone while making a try-saving tackle and left the field to be checked for concussion. He looked set to return at the 55-minute mark but was frustratingly over-ruled by the team doctor, who benched him for the remainder of the game.

Around the same time Beale hurt his left shoulder while making a tackle and while he played on until the final five minutes he clearly struggled. Those two players fired in the first half as the home side matched the Brumbies across the park. O'Connor set up the Rebels only try, scored by their new recruit Scott Higginbotham in the 18th minute, while Wallabies five-eighth Beale was a constant danger.

Brumbies fullback Jesse Mogg was just as dynamic for his team, scoring a try and setting up another in the first half. Mogg, the two-try hero from the Brumbies win over the Reds, was first on the scoreboard in the fourth minute after Beale turned over the ball when he was crunched midfield. The fullback showed scintillating speed when he ran on to a Rathbone pass and then he burnt both O'Connor and Nick Phipps to the ball that he had kicked into the in-goal.

Mogg also set up their second try, scored by Rathbone, who has returned to Super Rugby after four years on the sidelines with a midfield break.

The Brumbies were quick to close their one-point halftime deficit, through a penalty strike by Christian Lealiifano and the momentum of the match quickly swung their way.

As the home side's injury toll mounted the Brumbies grew in stature. After skipper Ben Mowen showed his pace to scoop up a loose ball and charge to the line, they grabbed their bonus point with a fourth try in the 74th minute, scored by replacement back Robbie Coleman.

Beale was due to have scans on his shoulder with Rebels coach Damien Hill unwilling to speculate on the seriousness of his injury. He said O'Connor had already recovered from his head knock better than hoped.

Hill was delighted by his team's first half performance but said they lost composure when things didn't go their way later in the game.

"In the first half we stuck to the game plan and played with intent. The breakdown was good, the set-piece was good, defence was great ... we were in the game," Hill said. "The second half we seemed to go away from that a little bit and a little bit of panic set in, around those injuries I think. Against a team like the Brumbies, it's going to result in what you saw tonight."

Brumbies coach Jake White said his side showed great composure, led by skipper Ben Mowen and new recruit David Pocock. He said the calibre of players that the Rebels lost to injury made it difficult for them to remain competitive. Mowen felt his side was out-enthused early on.

"We needed to flick that switch mentally," Mowen said. "The second half was much better."