They beat North Harbour Hibiscus 39-13 at Forsyth Barr Stadium this afternoon.
Winger Jamie Church lifted her try tally to 10 this season, scoring a hat-trick to help the Spirit on their way.
Fullback Sheree Hume was instrumental at the back, scoring two tries of her own.
The Spirit were outstanding defensively across the park, pressuring the Hibiscus high and forcing them in to errors.
Cheyenne Cunningham got the Spirit under way.
She picked up a ball that had been knocked down by a Hibiscus player 5m out and scampered across the line to lead 7-0.
Spirit flanker Leah Miles was in the thick of everything defensively.
That effort rippled across the Spirit, with her team putting on a brick wall that the Hibiscus struggled to get through.
Church added her first of the day with a piece of individual brilliance.
She picked up the ball on halfway and spotted a gap down her wing, finishing off her team’s second try of the afternoon.
Their defensive effort was put to the test again — and withstood every time.
The Hibiscus strung together long phases, and had majority possession first half, but could not break through.
It took the Spirit being penalised for being offside for Freeman to bang over another to be rewarded.
But the Spirit hit back almost immediately.
Hume went on a dazzling run, taking the ball out wide and holding it up to look for Church on the wing.
It sucked the Hibiscus defenders out to cover Church, leaving Hume to finish it off herself, complete with her trademark fin up, to lead 19-16 at halftime.
The Hibiscus finally made something of their opportunities, opening the second half scoring.
But that was the only joy for the Hibiscus in the second half after the Spirit lifted their intent.
Church added her second before Keely Hill put her in the right space to do it all again.
Hill — taken out in a questionable tackle after her offload — sped away down the left, dishing off to Church who yet again finished it off.
Hume added another, before she hobbled from the field, and Miles scored as well, giving the Spirit a comfortable 39-13 win.
They head north next week to take on Northland in their semifinal.
A minutes silence was held before the game in remembrance of former Otago president Graeme Renton and Otago rugby chairman Ron Palenski, who died recently.