The Otago Spirit's bubble burst when it was beaten 13-11 by Counties-Manukau in Pukekohe on Saturday.
Otago has now lost its chance of making the national championship final and will need to beat Manawatu in Dunedin this Saturday to hold on to its third spot.
It was Otago's second successive loss, after winning its first four games, and it now trails Canterbury and Auckland, the teams which will fight out the final.
Canterbury leads the championship with 24 points and is followed by Auckland 23, Otago 19, Manawatu 16, Waikato 15, Wellington 12, Counties-Manukau 11 and Taranaki 0.
Scores were level at 8-8 at halftime but Counties-Manukau scored a second try after the break to win only its second game this season.
Otago dominated the set pieces. Its front row of Pip Love, Lucy Emery and Gemma Tuhega pushed Counties back in the scrum and made ground with the pick and go. Otago also won its share of ball in the lineout, where flanker Rachel Scott played a key role.
However, the ball the forwards provided was not used efficiently. The backs took wrong options and silly mistakes were made.
Otago was also out-manoeuvred in the rucks and mauls and the backline was shut down because of the bustling tactics and big hits made by Counties-Manukau. It was a bruised and battered Otago team after the game.
The front row excelled and the other Spirit forward to stand out was Scott with her mobility. She was good with the ball in hand and made some telling tackles.
The best Otago back was second five-eighth Greer Muir with her ability to crash the ball up and make line breaks.
Fullback Haile Hurring was dangerous on the counterattack and her ability to read the game helped Otago stop dangerous attacks.
In other games, Canterbury beat Manawatu 36-18, Auckland thumped Wellington 46-0 and Waikato beat Taranaki 41-5.
Women's championship
The scores
Counties-Manukau 13
Jonsal Tautari, Aotearoa Matau tries; Hazel Tubic pen
Otago Spirit 11
Michaela Baker try; Anika Tiplady 2 pen
