The Nuggets smothered the Hawks from start to finish, at times hanging tough when the scoring dried up, and eventually emerging 91-80 victors.
That defence was a hallmark of their early-season dominance and, when it matters most, the team has rediscovered it.
The win means the Nuggets will now play the Nelson Giants in Friday night's semifinal.
Tray Boyd was exceptional in putting up 30 points on 11-of-17 shooting, while Keith Williams and Nikau McCullough had 24 and 19 points respectively.
But it was Todd Withers, who posted just three points and five rebounds, who was the Nuggets' star in this one.
The import forward dominated the game at the defensive end.
He came up with big play after big play and shut down the Hawks' key threats inside.
Sam Timmins was similarly key in that regard on the inside, while Matthew Bardsley had moments of exceptional full court defence in his nine minutes.
"The guys were talking in the van about locking in when that pressure comes on and when they score," Nuggets coach Brent Matehaere said.
"Making sure we get locked in back on defence, and defence turns into offence when they get away on it. We did a few times.
"I'm really happy with the guys and their efforts out there. Sometimes in life you get half a chance and it's about taking that half chance."
Both teams had a nervy start, but the Nuggets gained some separation as Williams went on a run late in the first quarter.
They took a 22-15 lead to the break, and while the game stayed messy through the second quarter, Withers' and Timmins' presence helped the Nuggets keep their leg up.
Boyd made it 40-30 when Hyrum Harris fouled him on a three-pointer, but the Hawks finished strongly to bring it back to 42-35 at halftime.
McCullough drew a charge on Harris to open the third quarter - Harris's third foul.
The Hawks star then proceeded to take over the game, pulling them back to within two.
But he had been aggressive and taking risks to do so, and that backfired minutes later, as he fouled Boyd going to the hoop - picking up his fourth foul and being left to go to the bench.
It was a turning point.
The Hawks hung around and brought the deficit back to two again, but the Nuggets pulled away early in the fourth quarter.
McCullough began coming up with some big baskets and it was one of his triples that made it 68-56.
From there the Nuggets always had the Hawks at arm's length, continuing to battle to close out the game.
In the late game, the Auckland Tuatara beat the Wellington Saints 92-87, ending the defending champions' run.
The Tuatara face the Taranaki Airs in the other semifinal.
Nuggets 91
Tray Boyd 30, Keith Williams 24
Hawks 80
Ethan Rusbatch 29, Hyrum Harris 16
Quarter scores: 22-15, 42-35, 58-51
- ODT