The Melbourne Rebels have snapped the Brumbies' unbeaten start to the Super Rugby AU season with a comprehensive 30-12 win at Leichhardt Oval on Friday night.

The Rebels scored four tries in a first-half blitz to shatter the Brumbies' nine-game winning streak against Australian rivals in the torrential Sydney rain.

The hosts have been locked out of their home state but showed little concern to score 27 points in the opening stanza, securing a bonus point and mark their best first half played outside Melbourne.

To date the Brumbies have been placed on a pedestal in the domestic landscape having not tasted defeat against an interstate rival since March last year.

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However all but one of their wins in the Australian iteration of Super Rugby had been decided by eight points or less - and twice victory was snatched from the jaws of defeat.

"We've just got to really look at ourselves," Brumbies captain Allan Alaalatoa said post-match.

"In wet conditions, we need to play the field position better. That's something for us to review in the bye week.

"They stayed on top of us well, they kept putting balls in the corner and putting us in our end. In the first half we struggled to get out of our end

"Tactically we had it on the board, we knew what we wanted to do in the wet conditions. On the other side, we needed to deliver on that. It was a tough game. We needed to kick better."

Dave Wessels' decision to pick Andrew Deegan at flyhalf and push Matt To'omua to inside centre seemed an inspired one in the conditions in what was ultimately labelled one of the finest outings in the club's history.

For it seemed as though nearly every Rebels kick had the Brumbies on the back foot - not least of which that which led to a Reece Hodge try, while the visitors lacked the same penetration.

Joe Powell pinching the ball of the back of a maul was the Brumbies' only avenue across the line in the first half. Errors cruelled hopes of a revival, with a late Will Miller try all that saved the visitors from their lowest Australian derby score since 2011.

AT A GLANCE

Super Rugby AU round six: MELBOURNE REBELS 30 (Reece Hodge 2, Brad Wilkin, Jordan Uelese tries; Matt Toomua 2 conversions; Toomua 2 penalties) bt ACT BRUMBIES 12 (Joe Powell, Will Miller tries; Bayley Kuenzle conversion) at Leichhardt Oval.