Rebels head coach Damien Hill said he was impressed with his team's first half performance in their 13-30 loss to the Rebels which he put down to some poor decision making and injury-enforced substitutions.
The Rebels took a one point lead at 13-12 into half time but failed to add to their first half points tally and allowed the Brumbies to score 18 unanswered points.
Hill said that the injury enforced replacements affected the ability of the side to compete for the full 80 minutes.
"They were outstanding (in the first half)," Hill said. "They stuck to the game plan, played with intent and the set piece and breakdown were very good. "
"Defence was good and we got the ball to space, but in the second half we seemed to step away from that a bit. A little bit of panic set in with the injuries, and we probably ran the ball a few times when we should have kicked for position."
Hill said that Beale and O'Connor will be assessed in the next 48 hours, and wasn't prepared to speculate about the flyhalf's injury.
"We will wait for the medical staff to scan Kurtley. He has had that injury before, so we will just have to wait and see how it is. "
"James just had concussion, and there is protocol in place for these things, and in the doctor's opinions he wasn't right so it was in his best interests not to return to the field."
Captain Gareth Delve was disappointed with the result, but suggested that the team will move on as quickly as possible and focus on the Waratahs ahead of the first away game of the season next Saturday.
"Clearly we lost the battle of the game in the second half, and against a clinical team like the Brumbies they take advantage of it. In the second half, we let them get a roll on and their ball retention was good, and they got in behind us and made us pay."
Delve believes high profile code-hopper Israel Folau will be a threat, but that there are many different threats that the Sydney-siders pose.
"The Waratahs have an exciting backline, but that is just one of the threats. Their forwards will be a challenge that was pretty similar to what we faced tonight, and If we let them dominate then they will be able to create plenty of space for Folau. "
"Izzy is certainly a fairly unique threat with his high ball, but we are confident we will have the game plan to put in place to deal with that."
The biggest roar from the crowd was reserved for the introduction of hooker Shota Horie, who became the first ever Japanese import to play for an Australian Super XV side.
Reflecting on his debut, Horie said he felt at home in Melbourne already, but he was not underestimating the size of the task at hand.
"The fans and players have been very welcoming," Horie said.
"When I ran on I could hear just how much support there is for me in Melbourne. The physicality of the game is new to me; Super rugby players are very strong, and I felt that out there."
One positive of the game was the Rebels' set-piece. The scrum more than held their own against a world-class front row, and a couple of early shaky lineouts soon made way to a proficient and effective lineout, with Delve at the forefront of it.
Delve took eight throws before being replaced on the hour mark, nearly half as many as he caught all last season, and was happy with how the lineout worked.
"It was good from Hugh Pyle to identify where the space is and call it accordingly."
"We have done a lot of work on our lineout across the board and we are really happy with where it is at right now, and the credit for that should go to 'Pyley' and Matt Cockbain."
"I had a few more takes than usual, and hopefully that helped us create a bit of space."
The Rebels travel to Sydney next week where they will hope to end their losing streak to the Waratahs.