Kate Heffernan was busy on defence, picking up valuable ball in the midcourt before the Mystics could get close enough to feed star shooter Grace Nweke.
The Steel attackers were unflappable, with the connection between feeders Shannon Saunders and Gina Crampton and mid-season shooting addition Ellen Halpenny growing every game.
A 13-8 final quarter comeback from the Mystics avoided a blowout scoreline for the Northern side, who were down by 12 towards the end of the third quarter.
The powerful finish meant that the Mystics were rewarded with a bonus point, which could make a difference in determining the race for the final.
On the other hand, 2020 will be the first year that the Steel won't contest the final, and will need to claim at least another win against the top two teams - the Tactix and the Pulse, who they play tomorrow night in Invercargill - to make the third v fourth playoff match.
That race for fourth will most likely be against the Northern Stars, whose mathematical chances of making the final are now over.
* The Pulse aren't 100% confirmed yet to make the final, but they only need one more point, so let's be realistic.....