Cheika has had subtle digs at the Brumbies this season and didn't take long to fire the first barb on Sunday, claiming  the Brumbies wanted to play the Waratahs in this weekend's semi-final because they thought they had a better chance beating them than the Canterbury Crusaders.

When the two teams met two weeks ago, Cheika questioned the legitimacy of the Brumbies' massive injury list. It was a game the Tahs won easily, with Cheika using  a tweet from former Brumbies fitness guru Dean Benton as motivation.

Benton had claimed the Brumbies worked harder than their NSW counterparts.

The Brumbies sent Cheika the bill for the broken coach's box door that was smashed after the Brumbies' convincing win in Canberra earlier this year.

Cheika has used the term poker face to drum into his team the importance of not giving his opponents any ammunition and it's a mantra the Brumbies seem  to have been taken up as well.

Although Tahs lock Jacques Potgieter might have dropped his guard when he labelled his team unstoppable in their quest for a maiden Super Rugby title.

Brumbies coach Stephen Larkham had only praise for NSW's season so far - a sentiment echoed by flyhalf Matt Toomua.

Larkham will face a selection headache in the back line, with Clyde Rathbone and Andrew Smith available for selection after overcoming hamstring niggles. The forward pack should be fairly settled, with no further injuries to come out of the qualifying final win against the Waikato Chiefs.

Larkham said the Waratahs' confidence was well-placed.   "They've certainly had a very good year, they're the first-ranked attacking team and the first-ranked defensive team,'' he said.

"They're sitting on top of the ladder for a reason ...  There's obviously a bit of confidence for them to say something like [they're unstoppable] ... I can understand where the confidence is coming from."

Toomua will form part of a star-studded Brumbies back line that comes up against a star-studded Waratahs back line. It will pit the ACT No. 10 against incumbent Wallabies flyhalf Bernard Foley and the Waratahs inside-centre Kurtley Beale.

All three are candidates to wear the Wallabies No. 10 jersey.

"There's so much strike power in that back line and, to be fair, the whole team,'' he said of the Waratahs. "They've got some really good runners in the forwards that generate that go-forward ball - but their back line's been the form back line of the competition.

"There's no secret - they've got a lot of try-scoring ability, with guys like Kurtley and Bernard, who set it up really well. We'll have to be good [to beat them].

"A lot of guys have gone in confident and had their pants pulled down."

SUPER RUGBY SEMI-FINAL

ACT Brumbies v NSW Waratahs

Sydney Football Stadium, Saturday, 7.40pm