Why the Brumbies ‘need’ a winning bonus point against embattled Waratahs

The ACT Brumbies are out to pile on the tries against an embattled NSW Waratahs, with every bonus point key in their quest for a top-two Super Rugby Pacific finish.

The Brumbies have their work cut out to haul in the second-placed Blues, who sit six points above them with four regular-season rounds remaining.

But with the Blues playing the ladder-leading Hurricanes on Saturday, Stephen Larkham's charges will be eager to close the gap on the top two and a home semi-final spot.

"We're very conscious that we need bonus points to get to where we want to get to at the end of the season," the Brumbies coach told reporters on Thursday.

The second-from-bottom Waratahs will be determined to upset their local rivals, with a finals place of their own still not out of the question.

The Brumbies have freshened up their squad to face the Tahs, with Jack Debreczeni named in the No.10 jersey for the first time this year, but maintain they won't be taking their opponents lightly.

"We know how important this game is for both teams," Larkham said.

"There's always lots of emotion at the start of these games ... and we're also conscious of not burning too much energy through the week.

"They've still got lots of individuals who are quite dangerous with ball in hand.

"The situation that they're in, in terms of where they are in the ladder and what these last four games mean to them, we're just expecting a lot of physicality."

Prop James Slipper will start on the bench for the Brumbies after battling a niggling back issue against the Fijian Drua last time out.

In another boost for Larkham's side, winger Ben O'Donnell has been named on the bench as he makes his long-awaited return from an anterior cruciate ligament injury.

"It's been a long journey for Ben," the coach said.

"His rugby IQ is fantastic, his skill-set is very versatile  and we expect him to add a lot of confidence to the team and the players around him."