However, while it can be seen as an upset Otamatea have had a great start to the season as they now have five wins and sit third on 25 points - five off top spot, which is held by Hora Hora.
In Hikurangi, Waipu let a win slip by as they had the chance to secure a strong start to the season but lost 25-23.
Had Waipu won, they would be sitting inside the top four by one point.
In other results, Hora Hora comfortably saw off the Western Sharks challenge to win 51-21 and Wellsford came out on top in a tight match with Mid Western, winning 29-27.
Results:
Southern Districts Premier
Hikurangi 25 Waipu 23
Old Boys-Marist 37 Kamo 17
Otamatea 41 Mid Northern 39
Wellsford 29 Mid Western 27
Hora Hora 51 Western Sharks 21
Southern Districts Premier Reserve
Hikurangi 59 Waipu 0
Old Boys Marist 44 Kamo 14
Mid Northern 27 Otamatea 0
Wellsford 21 Mid Western 15
Western Sharks 53 Hora Hora 17