The semifinals are set in Dunedin premier club rugby.
Southern soaked up some early pressure to romp to a 41-15 win over Zingari-Richmond, who had a player shown a red card in the second half.
Southern will play Green Island, and Dunedin will host University, next Saturday.
Top qualifiers Green Island were beaten 31-25 by University at Miller Park this afternoon, but the Grizzlies survive for another week as the highest-ranked loser.
The Magpies are now the highest-seeded team, and on the evidence of today’s win will take some beating.
Dunedin beat Kaikorai 39-20 to claim the final spot in the semifinals, where they will have their hands full with a University team hitting their straps.