The Sparks had a six-wicket win over the Northern Brave at Bay Oval this afternoon.
The victory shifted the Sparks to the top of the table on 28 points.
Wellington, who have now dropped to second, sit on 24 points, still play Auckland (Monday) and Northern (Thursday) and will go in favourites for those games.
If they secure victories, Otago will fall back to second or third place – and will then play in the elimination final.
Northern (16 points) and Auckland (14 points) are still vying to secure their playoff spot.
Earlier today, Sparks captain Hayley Jensen was fantastic and whacked 49 runs off 34 balls to help her side home.
Otago made a great start with the ball when Emma Black opened with a maiden over in a great spell from the seamer.
Eden Carson picked up the prize wicket of Sri Lankan Chamari Athapaththu with her first ball.
Otago restricted Northern to 29 for one at the end of the power play and then removed the danger woman two overs later.
Northern captain Jess Watkin – who was superb when she faced the Sparks in Dunedin last time – was caught deep by Carson for 31.
Samantha Barriball was then bowled by Felicity Robertson for one and Nensi Patel cut her shot straight to Gordon for two.
Otago picked up wickets at regular intervals and Jensen trapped Northern top scorer Caitlin Gurrey for 39.
Northern started to crumble and finished at 127 for eight at the end of their innings.
Suzie Bates and Bella James set the Sparks off strong in reply, before Bates skied a shot and was caught.
James was then stumped for 17 and the Sparks were 44 for two in the fifth over.
Jensen was promoted up the order and came in at No 3 for the Sparks, and was joined by Olivia Gain.
Gain did not last long and went for two, leaving the Sparks 48 for three at the end of the power play.
While it was not the ideal scenario, the Sparks were still on track and ahead of where Northern were at the same time.
Jensen started to wind up, dropping down to one knee to pummel a big six down the ground.
That helped propel the Sparks forward and pushed them forward.
Polly Inglis found the gap for four to give Sparks a six-wicket win.
