Stephen Murdoch (32 off 27) eased the scoreboard pressure in the next over, hitting four consecutive boundaries off Ajaz Patel.
Blair Tickner then entered the attack and took three wickets in his first two overs to have the home side reeling at 48-4 in the 8th over.
Cam Fletcher (65* off 37) didn't give the chase away and he shared a rapid 53-run stand with Henry Shipley (27 off 15) for the 7th wicket that gave the home crowd hope for another grandstand finish.
However, when Shipley became Tickner's fourth dismissal of the evening the visitors had the four competition points in the bank.
The result lifts the Stags up to 18 points, level on points with the Otago Volts but with a slightly better net run rate. They sit two points above the Auckland Aces, although the Volts and Aces each have a game in hand.
The Wellington Firebirds sit six points clear at the top of the table and are almost certain of a spot in the top three. Which two teams will join them in the finals is less clear with final standings set to go down to the wire and all teams except the Knights in with a chance.
The Aces finish their round-robin with fixtures against the Knights and Firebirds. The Volts and Stags meet in a crucial matchup in Dunedin on Saturday before the Volts finish with the Canterbury Kings at Hagley Oval.