South Canterbury have taken a three-point lead from Whanganui, while North Otago's golden point loss to Mid Canterbury has allowed Thames Valley, who beat Wairarapa Bush 37-19, to move into third place on 15 points, one point behind Whanganui who have 16.
Buller beat West Coast 36-32 to claim fourth while Mid Canterbury, and Horowhenua Kapiti, who beat King Country 25-18 are hot on their tails.
The story of the weekend belonged to Ngāti Porou East Coast who edged Poverty Bay 12-10 in an arm-wrestle in Gisborne to secure the Bill Osborne Taonga.
Bunnings Heartland round 4 results:
Horowhenua Kapiti 25 (Callum Pointer-Watts try; Jack Tatu-Robinson con, 5 pen; Tyler Tan pen) King Country 18 (Cruise Dunster, Kaleb Foote tries; Quinn Collard con, 2pen ). HT: 6-7
North Otago 35 (Scorers not provided) Mid Canterbury 40 (Isireli Masiwini, Raitube Vasurakuta 2, Manasa Samo, Logan Bonnington tries; Tom Reekie 3 con, 3 pen). HT: 5-20. FT: 35-35
Poverty Bay 10 (Shayde Skudder try; Moses Christie con, pen) Ngāti Porou East Coast 12 (Hoani Te Moana, Jody Tuhaka tries; Carlos Kemp con). HT: 3-7
Thames Valley 37 (Ben Stephens, Zach Clark, Zane Heath, Will Newbold, Connor McVerry, Leeroy Neels tries; Todd Doolan 2 con, pen) Wairarapa Bush 19 (Tristan Flutey, Inia Katia, Tafa Tafa tries; Ben Brooking con; Tipene Haira con). HT: 15-12
Whanganui 24 (Timosi Serawalu, Alekesio Vakarorogo, Semo Vodosese tries; Ezra Malo 3 con; Ethan Robinson pen) South Canterbury 30 (Leatigaga, Russell, Liueli, Vaka Taelaga tries; Sam Briggs 2 con, 2 pen). HT: 14-19
West Coast 32 (Eliott Smith 2, Joseph Scott, Jamie Garland tries; Ben Wyness 3 con, pen; Logan Ross pen) Buller 36 (Alex Lean, Jack Parker, Isei Lewaqai, Anthony Ellis, Michael Stringer tries; Jack Parker 4 con, pen). HT: 20-15