The visiting side posted 300 for seven yesterday and 308 for five the day before.
That was too many for the defending champion on both occasions.
Wellington (30 points) has clinched a spot in the final with two round-robin games remaining.
Canterbury (22 points) is well positioned to join it.
Central Districts (15 points) and Auckland (15 points) will need results to go their way, while the prospects of Northern Districts (12 points) and Otago (12 points) live on only in a mathematical realm.
Sparks coach Craig Cumming was upbeat about the way his side batted. But Otago conceded too many wides — more than 50 — over both games.
"There was some really good stuff," he said.
"I’m really pleased with both batting performances, but we had to be good because we were chasing 300 both days.
"So from a bowling and fielding point of view it was a really good lesson on what 50-over cricket is about.
"That is the area where we need to do a bit more work."
Key Auckland batter Katie Perkins, who was fresh from a century the day before, made 94 from 107 balls yesterday. Her presence at one end allowed Auckland to attack from the other.
Bella Armstrong muscled 44 from 42 and Prue Catton clipped 32 from 26, while opener Saachi Shahri made a valuable contribution with 51 from 75 to help set up the onslaught.
Gemma Adams removed talented opener Anna Browning for 16 and picked up three late wickets to finish with four for 44. She was the pick of the Otago bowling attack.
The Sparks lost both openers cheaply, but Olivia Gain and Caitlin Blakely started stitching the chase back together with a dangerous partnership of 71 from 92 balls.
That promise was snuffed out when Gain took off for a single, got sent back and did not beat the throw from Amberley Parr-Thompson.
It brought an end to a sparkling knock of 48 which featured a couple of crushing pull shots and one very exquisite cut shot which sped to the rope.
Blakely, who made 78 not out on Saturday, got through to 51 before she hit a towering catch to midwicket.
All hope now rested with the captain Felicity Leydon-Davis and Polly Inglis, who had been left a mammoth job.
The pair looked like they might just do it as well. But Inglis was cut off on 54. Saachi Shahri made a terrific catch at point to bring the 101 stand to an end.
Leydon-Davis (59) gambled on getting back for a second but was undone by a good throw to the keeper from Josie Penfold.
Otago was eventually restricted to 272 for nine, 29 runs short of victory.
On Saturday, Auckland thumped 308 for five and rolled the Sparks for 243 to win by 65 runs.
Perkins struck 10 fours in her knock of 113, while Holly
Huddleston also had a memorable match.
She swatted an undefeated 49 from 38 balls and took four for 49 with the ball, including the first hat-trick by an Auckland Hearts player in either of the white-ball formats.
It was just the sixth hat-trick in women's domestic one-day history in New Zealand.
In the other games, Canterbury split the honours with Central Districts, while Wellington recorded back-to-back wins against Northern Districts to cement its spot in the final in Queenstown on March 4.
