The Sparks needed two runs for a win — one for a tie — off the final ball when Hearts bowler Brooke Halliday snuck the last delivery past Emma Black.
It landed with wicketkeeper Izzy Gaze who smacked the bails to secure a one-run victory for the home side in Auckland yesterday.
It was a dramatic finish to a game in which neither team really held momentum with the bat on a tricky wicket.
But the Sparks deserve their plaudits for how they attacked the innings.
When the boundaries dried up, they ran hard for the twos and threes and gave themselves every chance to hunt down the win.
PJ Watkins, who finished unbeaten on 36, spent much of her innings supporting, running hard to keep the Sparks in it until the final over.
White Fern Molly Penfold finished with career-best figures of three for 15.
Chasing 124, Bella James scooped the first boundary for the Sparks and drove another down the ground.
Felicity Robertson skied her shot to be dismissed, but James and Caitlin Blakely pushed hard for the runs.
Blakely was caught behind on the last ball of the power play, leaving the Sparks 33 for two.
An overthrow allowed the Sparks to bank a couple of extra runs and then James swept a sweet shot to the boundary before she succumbed to a slower ball from Josie Penfold.
Back-to-back wickets for Molly Penfold changed things as she removed Polly Inglis and had Anna Browning caught behind for a duck.
Olivia Gain went the next over, putting the Sparks 91 for six in the 16th over.
Gray was trapped lbw in the penultimate over leaving Watkins and Black to take the Sparks agonisingly close.
Earlier, Gray struck gold with her first ball taking the wicket of Prue Catton.
Black bowled Gaze the next over leaving the Hearts 13 for two.
The Sparks squeezed the Hearts through the power play and reduced their scoring opportunities, leaving them 26 for two.
Veterans Maddy Green and Halliday pulled the Hearts innings through.
They ran hard between the wickets and timed their shots nicely.
Green pulled her shot to the boundary and Halliday whipped another behind square to bring up the Hearts’ half century.
Browning finally stopped their partnership, dismissing Halliday for 32, leaving the Hearts 76 for three.
The Sparks employed eight bowlers to try make the breakthrough.
Robertson came up trumps, taking Green when she came down the wicket and hit it straight to James.
Bella Armstrong went for a duck when she too came down the wicket and was stumped.
Josie Penfold smacked a much-needed six and then was caught by James at long on to finish 123 for six.
