Auckland clobbered 291 for five to get themselves into the box seat.
Maddy Green led the way with a superb 126 and she combined in a monster 182-run stand with Lauren Down, who pummelled 90 from 89 balls.
Against an understrength Otago side, that should have been plenty.
The Sparks were without White Ferns duo Suzie Bates and Bella James.
Then a third White Fern was scratched late.
All-rounder Hayley Jensen pulled up lame during the warm-up and the defending champions had to scramble.
Eden Carson, who coughed and spluttered her way out to the field, was thrown the new ball.
The spinner was struggling with a chest infection but there was no way she was not going to play, even if it meant having to take a knee and catch her breath every so often.
Her courage was on display late in the game when she was called on to help win the game with the bat.
But first, the captain Felicity Robertson (53) and Polly Inglis (86) put on 148 for the third wicket to put the home side into a position to launch.
However, they both got out leaving fringe all-rounder PJ Watkin and Carson to hunt down the final 102 runs needed.
It could have been all over when Carson was dropped and almost ran out from the same play early in her knock.
Instead, the diminutive right-hander went on the attack. She smashed 59 from 43 balls and Watkins impressed as well with 47 from 60.
They kept defying the odds and chipping away at the target until they needed just eight from the last over.
But this rollercoaster of a game kept delivering the entertainment.
They needed two runs off the last ball and scrambled back for a second on a misfield.
Carson had run to the danger end while gasping for breath.
Somehow she willed herself to the end to complete the greatest run chase in the history of the Otago Sparks.
How is that for a fairy tale finish?
