The defending champions dispatched Northern Districts in back-to-back games at the University Oval at the weekend.
World Cup winner Suzie Bates was influential in her return to the Sparks.
She notched an unbeaten 51 to help Otago register a 37-run (Duckworth Lewis Stern method) win on Saturday and then clubbed 107 from 108 balls yesterday to help set up a monster 186-run win yesterday, the Sparks’ third-largest win by runs in the format.
The wins lift the Sparks to 30 points. They have a 15-point buffer to the second-placed Central Hinds.
White Ferns spinner Eden Carson played an important role yesterday as well. She took five for 24 to help rout the visitors for just 70.
It was the off-spinner’s second five-wicket haul in list A cricket and she told the Otago Daily Times the Sparks were "pretty happy with how we've been going this season".
"We’re trying to dominate with bat and ball and want to show lots of intent with both.
"And we also want to step up in the field where we can as well."
The game was not exactly going to plan early on yesterday, however.
Impressive seamer Marama Downes (three for 45) took two wickets with the first two balls of the match.
The 22-year-old right-armer got a delivery to shape away slightly and nip back off the deck to beat the forward defensive of the newly-promoted White Fern Bella James.
Caitlin Blakely went very next ball, trapped in front for a golden duck.
Downes got her hat-trick ball on target too but was denied that glory.
"I actually didn't see the first two balls," Carson said.
"I clapped them out and then made a coffee and then came back and they were sitting in the dugout and I was like, ‘Oh, this isn't good’.
"Yeah, I was like, ‘Oh, I might have to bat today’."
But with one Suzannah Wilson Bates down the other the end, the Sparks were able to wriggle out of trouble.
The veteran opener needed a life, though. She was dropped on 12 and that proved extremely costly for the visitors, who produced a clumsy performance in the field.
Other than that blunder, Bates showed her class. She was strong square on the offside and danced down the wicket to send the ball flying in the direction of long-on several times.
She pulled out the scoop shot deep into the 90s as further evidence she was feeling in complete control.
Olivia Gain was looking just as assured. The pair put on 114 for the fifth wicket.
Gain looked on track for a huge score as well, but inexplicably ran herself out on 55.
She turned to take off for a second run when the return throw had already reached the bowler, who rolled the ball under arm at the stumps from a metre away to run her out.
Put it down to lapse in concentration, but Gain had played so well up until then.
Bates had brought up her 28th list A century a few moments earlier when she punched the ball down the ground for single.
Her fine knock came to an end when she sliced a catch to Jesse Prasad.
Hayley Jensen (21 from 19) and Anna Browning (19 from 20) chipped in with some useful runs to help the Sparks post 256.
Carson took over from there.
In New Plymouth, Central Districts beat Canterbury in both games and Wellington did the double against Auckland at Eden Park Outer Oval.
