Auckland Aces' win over Canterbury Kings at Eden Park Outer Oval booked their place in the Super Smash finals.
The home side won by four wickets with 14 balls to spare to join Northern Knights in the finals, with just one more place now up for grabs.
Canterbury are still in the mix to make the top three, along with Wellington Firebirds and Central Stags.
The Kings were restricted to 145 batting first, as left-arm spinner Ronnie Hira took 4-26.
He claimed the wickets of Nick Kwant and Chad Bowes in the opening seven overs as the visitors slumped to 33-5.
They then recovered as wicketkeeper Cam Fletcher and captain Andrew Ellis combined for a sixth-wicket partnership of 87 off 67 balls.
But when Hira returned he claimed Ellis - for 40 off 30 - and Tim Johnston, with the next ball. Fletcher was then run out by Hira for 46 off 42 in the penultimate over.
The Aces lost Glenn Phillips for a duck in the first over and were 51-3 at the end of the six-over power play.
Mark Chapman made 23 from nine deliveries and Sean Solia went for a run-a-ball 17, but Auckland remained well ahead of the asking rate.
Captain Craig Cachopa settled in along with Robbie O'Donnell to steer the home side home.
Cachopa was out for 41 off 29 balls, while O'Donnell went on to make 55 off 42, falling only once the finish line was in sight.
Kings seamer Kyle Jamieson was tidy in his four overs, taking 2-23, but didn't get the support he needed.
Auckland are 1.36 to win their next game against Otago Volts, who are 3.20.
View all Cricket betting