But the ACT Brumbies are set to get a major boost when they return to action after next week's bye with the cavalry set to be called in to continue a spirited rivalry.

The Brumbies' unbeaten start to the domestic competition came to a shuddering halt in a 30-12 loss to the Melbourne Rebels at Leichhardt Oval on Friday night.

But Dan McKellar could soon call upon Wallaby scrumhalf Nic White, the competition's form winger Tom Wright, and prop James Slipper to bolster his playing roster.

White has rejoined the Brumbies ranks early after his deal at Exeter came to an early finish, with McKellar confirming he will enter calculations for a clash with the NSW Waratahs in round eight.

Wright and Slipper could return for the Canberra Stadium clash after they were both left out of the side to face the Rebels this week to manage niggling injuries.

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Tom Ross will undergo concussion protocols having came from the field in the 77^th minute for a head injury assessment after coming off second best in a heavy collision.

Paint it how you like, 18 points is a mark that will leave the Brumbies seething.

A late Will Miller try saw the Brumbies narrowly avoid their biggest defeat since they were put to the sword in a 43-14 thrashing against the Wellington Hurricanes on March 1 last year.

The 18-point margin against Melbourne also went within a whisker of pipping the number set in identical 36-14 defeats against the Canterbury Crusaders and Queensland Reds last season.

The loss marks the Brumbies' second of the year - their first was a heartbreaking one-point defeat at the hands of the Otago Highlanders in the globe trotting version of Super Rugby.

The Brumbies' seven-point buffer at the top of the Super Rugby AU ladder has been sliced to four, setting up a grandstand finish in the run to the finals.

Allan Alaalatoa's crew seemed to have one foot in the door of a home final, but their first defeat of the campaign sees Melbourne move to 14 points - four in arrears of the Brumbies on 18.

The Queensland Reds have now dropped back to third in the standings on 11 points, but they too have a chance to close the gap when the meet the Waratahs at the SCG on Saturday.

The top team earns hosting rights for the final, with second and third to play off for a spot in the decider. This competition might be about to go to another level.

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.