Otago will host the State Twenty20 cricket final next Sunday thanks to a 42 run win in the top two clash with Auckland at Eden Park.
Auckland won the toss and decided to bowl but Craig Cumming guided Otago to 163 for eight with 76 off 46 balls while Brendon McCullum hit 26 off 18.
Otago were in control from the start of Auckland's innings, taking three wickets in the first two overs.
Auckland's loss leaves third-placed Canterbury with a chance of making the final in Dunedin.
However they lost the toss in Palmerston North and after a delayed start Central Districts made 144 for six, Matrthew Sinclair top-scoring with an unbeaten 85.