Defending champions the Auckland Hearts suffered a shock 25-run loss at the hands of a side that won only two matches last season.
Tauranga whizzkid Nensi Patel, 14, made her one-day debut in the Spirit XI and claimed the important maiden wicket of Anna Peterson.
Batting first, Northern Spirit's tally of 226/7 was underpinned by a Spirit record for the second wicket. Opener Natalie Dodd (who top-scored with 93) and Emma Parker's 154-run partnership eclipsing the 127-run mark that had been set by Dodd and Anna Peterson - now bowling for the opposition - at Mount Maunganui in 2012/13.
Parker reached a career best 48 before Hearts bowler Regina Lili'i fought back to pick up 4-47.
Spirit also had the services of former Proteas Women wicketkeeper Bernadine Bezuidenhout, who is working her way through a two-year international stand-down period after shifting to New Zealand, as well as Scotland internationals Kari Anderson and Katie McGill.
By 129/7 in the 34th over, the Hearts still needed a further 88 - and a big finish from their tailenders to get across the line.
White Fern Holly Huddleston and Lili'i appeared to have answered the emergency call with a 60-run partnership for the eighth wicket, Huddleston top-scoring with 43 before she was crucially run out by Tauranga's Sam Curtis with a further 38 runs still required.
Curtis claimed debutante Feala Vaela Pula to have the Hearts 199/9, with 28 runs required from the last 4.4 overs.
But the Hearts would only manage two more singles before Curtis struck again in the same over, claiming a first-up win with her new team against her old teammates.