The Brumbies have plenty of work to do if they are to make an impact in the Super Rugby Pacific finals with their chances of a top-two finish over after a 31-21 loss to the Chiefs.

Missed tackles and butchered opportunities deep in attack cost the Brumbies a chance to roll the competition leaders at GIO Stadium.

They were competitive early before 24 unanswered points saw the Chiefs blow the game apart.

The loss leaves the Brumbies fourth on the table and likely to remain in that spot with a win against Melbourne next weekend, setting them up for a home quarter-final against the Hurricanes in a fortnight.

And they might have to do it without captain Allan Alaalatoa, the Wallabies prop helped from the field in the second half with a calf injury in what would be a monster blow.

Their defence held up well for the most part, although a clever short-side run from No.8 Luke Jacobson and an intercept try for Cortez Ratima let the Chiefs take control.

All Blacks contender Shaun Stevenson slashed through the line within five minutes after coming off the bench, their run of 24 straight points ended by Brumbies winger Corey Toole's try 10 minutes from fulltime.

No.8 Pete Samu crossed after fulltime to further reduce the margin.

The Brumbies had 65 per cent territory in the first half and were unlucky to go to the break trailing by 10 points, unable to find any points from a crucial 18-phase stand on the Chiefs' line late in the term.

The Chiefs, who have ploughed through most of the competition this season and only lost once, physically imposed themselves on the Brumbies and broke tackles easily to eat up post-contact metres.

So often able to rely on their rolling maul to get them out of trouble, the Brumbies only found one try off the back of their lineout from six inside opposition 22m, their set piece not firing against the powerful Kiwis.

In a potential battle of the respective national team fullbacks, Chiefs No.15 Damian McKenzie got the points over Tom Wright, initiating much of their attack and shifting the ball around at will.

Alaalatoa found himself in the sin bin early for a high shot on Brodie Retallick, although the Brumbies held strong and only conceded one penalty goal with the man disadvantage.