The Rebels could not make their man advantage count as Ryan Lonergan's heroics off the bench sealed victory for the Super Rugby AU leaders.
Ryan Lonergan's sensational kick after the siren sealed a 27-24 win for the Brumbies over the Rebels on Saturday.
The replacement scrum-half set up Tom Banks for a late try before scoring the winning penalty four minutes into additional time.
The unbeaten Super Rugby AU champions trailed 12-10 at half-time and had captain Allan Alaalatoa sent off for dangerous play moments before the interval.
However, the Rebels could only get on the scoreboard through immaculate kicking from Matt To'omua as they failed to turn their man advantage into tries.
To'omua kicked four penalties to give the Rebels their lead at the break after Len Ikitau's 20th-minute try following a Noah Lolesio grubber.
A penalty try handed the home side a boost eight minutes into the second half, but it looked as though ill-discipline would prove their undoing as To'omua's faultless kicking gave the Rebels the edge.
Then came Lonergan's divine intervention. Banks received his clever pass and dived beneath the posts, with Lonergan's conversion making it 24-21.
To'omua's eighth penalty of the contest levelled the scores with four minutes to go, only for Lonergan to have the final say, launching the winning kick through the posts from distance to spark wild celebrations in the nearby dugout.
The Brumbies stay top of the table and have now won 18 of their past 19 home games.
In the opening contest of the weekend, the Western Force likewise had to survive with 14 men on Friday as the visitors held firm to beat the Waratahs 20-16 in Sydney.
Hooker Dave Porecki's fifth-minute try and eight points from the boot of Will Harrison gave the home side a 13-0 lead, but that advantage was cut to three points in the space of four minutes, Jake McIntyre converting Fergus Lee-Warner's score before kicking a penalty.
Tim Anstee snuck over the whitewash but the Force were left with a battle on their hands after Andrew Ready saw red for swinging a punch during an off-the-ball clash.
Harrison squeezed over a penalty to cut the deficit to a point with seven minutes left, but Ian Prior stretched the lead to four in the closing moments as the Force saw out their first win since 2017.
