Otangarei fought hard but in the end were unable to get the result and will instead have to face Moerewa for a place in the final.
Moerewa have moved one step closer to the title with a strong 46-28 win over Hikurangi.
Moerewa have relied on their attack all season and for good reason. They have averaged more than 50 points a game for the year and again went close to topping that against the returning Stags.
Hikurangi enjoyed a strong return season in the RLN Premiership and recovered well from their opening round 84-6 drubbing at the hands of Moerewa.
They showed a lot of heart at Toll Stadium and managed to give Moerewa a bit of a scare as they ran in a few tries of their own.
But Moerewa were just too strong, particularly in the first spell.
RLN Premiership leading scorer Jaydenn Bentley-Hape opened Moerewa's account before barnstorming centre Te Tuhi Tipene crossed for his 26th try this year.
Brodee Palmer, DJ Palmer and Rock Wiki also added tries as Moerewa held a 30-16 lead.
Moerewa slowed it down with an early penalty goal in the second half to Bentley-Hape before tries to Wilson Hona, Wiki and Tipene sealed the deal despite Hikurangi's best efforts.
Wiki and Bentley-Hape picked up four goals a piece, taking Bentley-Hape's season points haul to an impressive 206 (25 tries and 53 goals).
Hikurangi added another two four-pointers of their own in the second stanza but it wasn't enough to stop the 18-point lead.
The major semifinal between Moerewa and Otangarei will be played at Toll Stadium on Sunday.