The Magic levelled the score with four minutes remaining in regular time, setting up a tense finish as the match went goal for goal in the dying stages.
Neither side blinked, with Jo Harten slotting a penalty goal with seconds left in regular time to send the match into extra time.
The Magic continued their momentum into extra time, with defender Leana de Bruin forcing the first break of the period to immediately put the Steel back in chase mode, from which they could never really recover as the homeside ran out 71-69 winners.
It was the first overtime match of the year after organisers controversially opted to drop extra time in regular season matches, letting drawn results stand.
Other than the extra time enthusiasts, there'll be one other group happy to see the match go into overtime - the Northern Mystics, the Magic's opponents in the New Zealand conference final on Monday night.
The two-day turnaround was already a daunting task for the winner of the elimination match, without throwing in an extra time game in the lead-up. De Bruin, the team's veteran defender, said her side will need to be fastidious with their recovery processes over the next two days.
"There'll be a lot of focus on recovery, I think I'm going to have to sleep in an ice bath for two days," 37-year-old de Bruin joked.
Monday's match between the Mystics and Magic in Auckland will determine seedings for the ANZ Championship semifinals, with the winner earning a home semifinal against the second-ranked Australian side, while the loser will have to travel to Australia to take on the best across the Tasman.
The Australian conference final will be contested tomorrow between the Queensland Firebirds and Swifts after the NSW side knocked out the competition's early pace-setters, the West Coast Fever, in Sydney on last night.