But the home side extended their lead in the 46th minute when loosehead prop Terina Williams scored and Tihore made it three from three with the boot.
The Sky Blues started their memorable comeback from an attacking scrum five metres out.
The ball went to the blindside for second-five Kaia Hayes Walker-Waitoa to score and reserve fullback Anahera Kirikiri added the trimmings (21-12).
In the 60th minute, Pounamu Wharehinga — deputising for Mullany-Mato — scored in sensational style to draw the Coast to within four points.
Following a Bay error from the restart, the Coast set a midfield scrum. Powerhouse McMenamin went left, found halfback Wharehinga, who ran 50m to score in the corner and put the Coast ahead with seconds to go.
Mullany-Mato, whose family donated the Rerepuhitai Trophy for competition between NPEC and Bay women's teams, was on cloud nine over her girls' fightback.
“That was a tough game,” she said. “The Gizzy girls really stepped up from when we last met (a 31-12 win to the Coast). They should definitely be proud of how far they've come.
“They capitalised on the opportunities that came their way in the first half but my ladies dug deep in the second. They showed true grit and determination to take that game and I'm very proud of our team.”
Both teams scored tries of high quality. With modern rugby's painful emphasis on defence, the cavalier nature of the national game is often absent, but not in this curtain-raiser.
The first try of the day was spectacular. Both teams had possession, 18 passes were thrown over the course of the ball travelling 100 metres from the Bay's goal-line to the black dot under the Coast's crossbar.
Poverty Bay coach, former men's senior representative and YMP club legend Ron Tamatea praised his team,
“I think that today we gained respect from the wider community. The girls were more confident - had self-belief. The commitment, passion, loyalty and eagerness to learn more, all the sacrifices they've made with home life, have definitely paid off.”
The good humour and calmness of Poverty Bay referee Les Thomas, with a lively crowd in, is to be commended.
The women's thriller was followed by a classic men's derby — the Coast making it a victory double for the Sky Blues with a 31-28 win.