A Desiree Miller hat-trick dashed the Brumbies' hopes of a shock Super Rugby Women's finals upset against the Waratahs at the Sydney Football Stadium on Friday night.

The Waratahs have advanced to a sixth grand final in seven years with a 47-27 win over the Brumbies, giving the unbeaten competition favourites a chance to cap off their redemption tale.

Waiting for the Waratahs in next week's final at Ballymore Stadium is the Fijian Drua, who have claimed back-to-back Super Rugby Women's titles since joining the competition in 2022.

"We're absolutely ecstatic. It is such a good feeling. The Brumbies really put a contest there so we really had to earn that," Waratahs captain Piper Duck said.

"After a pretty hard 12 months last year, the work we've done, I think it has really paid off. [The Brumbies] showed so much heart, and the quality of their contact is what got us tonight, but again, I'm really proud of the platform our forwards brought and set that platform for Desiree Miller to score a hat-trick."

The Drua booked their place in the final with a 25-14 win over the Western Force in Suva on Friday.

But winning this grand final looms as their toughest assignment yet. Just last month the Waratahs piled on 62 points against the Drua, determined to make amends for missing last year's grand final.

The Waratahs won the first four editions of the Super Rugby Women's competition before the Drua halted their dominant run.

"It's a semi-final. The Brumbies are always physical, they're always a tough match regardless, so I'm glad we could hold out and get that win," Miller said.

"If we just stick to our process and build on those one per centers, I feel like we'll have a really good shot [in the final]."

It will be cold comfort for Scott Fava and his Brumbies side, but no side had pushed the Waratahs quite like this so far this season - and in round one, they'd been beaten 45-10 by the same opposition.

The Brumbies are the only team to have scored four tries against the Waratahs this season, and there were moments some dared to dream only for the hosts to keep them at bay.

"We knew how we start the game was so important and the consistency throughout the full 80 minutes. It happened to us last week, we didn't get a good start, it happened again this week," Palu said.

"We've got to give credit where it's due. The Tahs wanted it more, they played the full 80, so they deserve it."

AT A GLANCE

Super Rugby Women's semi-final: NSW WARATAHS 47 (Desiree Miller 3, Maya Stewart 2, Georgina Friedrichs, Siusiuosalafai Volkman tries; Arabella McKenzie 6 conversions) bt ACT BRUMBIES 27 (Biola Dawa, Kate Holland, Sally Fuesaina, Allana Sikimeti tries; Faitala Moleka 2 conversions; Moleka penalty) at Sydney Football Stadium.

Ash Fernandez spent a season running up and down the sideline wishing she could get a ball in her hand.

Now? She's the voice of an ACT Brumbies' lineout plotting one of the most monumental upsets in Super Rugby Women's history.

Fernandez, who took up rugby after being inspired by Charlotte Caslick and Australia's Olympic gold medal-winning sevens stars, is preparing to face the NSW Waratahs in a do-or-die semi-final at the Sydney Football Stadium on Friday.

"Seeing how much she has grown and actually own that lineout leader position, her rugby IQ is growing, she's playing 80 minute games, it's a whole new level of game she's had that she has never had before," Brumbies captain Siokapesi Palu said.

"She definitely had itchy feet last year, being taken out [with a hand injury] in the first game. She's done so well, I've seen her rehabbing. Even through academy, she'd been running along the sidelines with no ball in her hands.

"That's really hard for rehabbers, to not be able to get their hands on a ball. She's done really well and it's come to fruition."

Standing in the Brumbies' way is an unbeaten Waratahs side which has dominated every rival this season.

Through five games, they boast a positive points differential of 136 - every other team's points differential is negative - and beat the Brumbies by 35 points in round one.

"This time last year, we were in the semi-finals for the first time ever. To be able to accomplish the same things this year - and hopefully further - is really exciting," Palu said.

"We're going to play against the Tahs obviously. We had them first round, but coming to them for a semi-final with a bit more time and a few more games prior to playing hopefully puts us in a better position."

The Waratahs have been bolstered by the return of Wallaroos captain Piper Duck, who missed the past fortnight with a foot injury.

"I did freak out a little bit," Duck said.

"It was quite scary but fortunately the physios reassured me it was quite minor so we've been really precautionary the last two weeks to make sure I came back ready and 100 per cent."

Ex-Brumby Michaela Leonard and the Western Force will face the Fijian Drua in Suva to open the semi-finals on Friday afternoon.

The grand final will be played at Ballymore Stadium on April 28.