However it was Northland FC who broke the deadlock in the 19th minute through Winstanley.
This prompted Rotorua to take a more conservative approach, given any more goals would prove catastrophic to their chances.
Northland kept the home side guessing through their play, providing a spectacle on a mix of attacking and defensive prowess.
The women from the north maintained a 1-0 lead going into halftime, bringing themselves within 45 minutes of a well-deserved promotion.
Trailing 7-3 in the tie, Rotorua came out from the halftime break all guns blazing.
Desperate for goals, they tried to break the wall that was Northland's defence.
But the eventual victors maintained their shape and discipline, clinching promotion with a goal from Sandle five minutes from time.
Coach Carl Compaan had nothing but praise for his team.
"I'm very happy. It wasn't in our wildest dreams to accomplish this much, given we only had 10 at our first training," he said.
"The big thing for us was that we kept on winning which kept the girls wanting to come back for more."
Northland FC will now move on to the country's top women's club league.
The promotion adds to the many accolades Northland FC have picked up this year.
Earlier in the season, Nicole Stratford led the way with four goals as they smashed Hibiscus Coast 7-1 to win the Federation One Cup at Toll Stadium.
Northland FC also have five players in the Northern wider training squad after impressive seasons: goal keeper Leah Botica, midfielder/forward Anya Gross, and defenders Alex Kelly, Nicole Stratford and Abbey Venmore.
