It sets up a big Saturday as Buller will be home to Horowhenua-Kapiti, with both teams looking to lock in a home Meads Cup semifinal.
Mid Canterbury stay in sixth behind Wanganui, but they can still get up to the Meads Cup by beating King Country in Taupo - preferably with a bonus point because if Wanganui defeat North Otago and the two sides finished tied, Mid Canterbury get priority due to winning the fixture between them two weeks ago.
North Otago currently have the high hand for the final spot in the Meads group after they picked up an expected 57-14 victory over East Coast in Oamaru and got the five points to move up - while also being the only team leading at halftime on Saturday to win their game.
Matthew Vocea and Josh Buchan each scored two of the home team's nine tries, with Buchan adding six conversions on a profitable day.
South Canterbury will be safe on top of the table with just winless East Coast left to play, but they flirted with disaster against Wairarapa Bush at home in Timaru, having to come from behind to win 29-20.
The Cantabrians have had major injury issues with five regulars unavailable, but were still expected to be comfortable winners until they found themselves trailing 17-12 at halftime, which became 20-12 after the break.
All Black Piri Weepu scored his first Heartland try, with first-five partner Tim Priest adding 10 points with the boot.
However, the home side rallied in the scrappy match, with halfback Willie Wright following up last weekend's hat trick of tries with a double, as well as two conversions, which guarantees a home semifinal with the formality of now securing top spot against East Coast.
West Coast ensured Thames Valley can forget about the Meads Cup group after they rebounded from their loss to South Canterbury to pick up a 24-17 victory in front of the faithful at Rugby Park in Greymouth.
Thames Valley were aided by a penalty try with an automatic conversion, but West Coast got four tries, including Nik Cumming getting one of them plus two conversions.
After a season to forget, Poverty Bay grabbed themselves a lifeline for making the Lochore Cup playoffs by facing a shellshocked King Country, coming off their mauling by Wanganui, and prevailing 43-29 in Gisborne.
After being tied 19-19 at halftime, Poverty Bay pulled away in the second half, scoring five tries by actual players and getting a penalty try of their own, with Andrew Tauatevalu finishing with a 16-point haul.
It means Poverty Bay's game against Thames Valley in Te Aroha will be a straight playoff to see who gets the final spot in the 5th-8th group for the right to play another weekend of football.
Results
North Otago 57 (Matthew Vocea 2, Josh Buchan 2, Connor Newlands, Don Lolo, Jared Whitburn, Inoke Naufhu, Dan Lewis tries; Buchan 6 con) bt East Coast 14 (Peehi Fairlie, Epeli Lotawa tries; Kris Palmer 2 con). HT: 35-7.
Buller 40 (Iliesa Ravudra 2, James Lash, David Egelstaff tries; Lash 4 pen, 4 con) bt Mid Canterbury 32 (Maleli Seu 3, Angus Lindsay tries; Jarred Percival pen, 3 con, Jason Kjestrup pen). HT: 29-13 Mid Canterbury.
Poverty Bay 43 (Andrew Tauatevalu, Sione Ngatu, Siosiua Moala, Kelvin Smith, James Grogan, Penalty try tries; Tauatevalu 4 con, pen) bt King Country 29 (Scorers not provided). HT: 19-19.
South Canterbury 29 (Willie Wright 2, Sireli Buliruarua, Vitali Tora, Brad Hemopo tries; Wright 2 con) bt Wairarapa Bush 20 (Epeli Rayaqayaqa, Piri Weepu tries; Tim Priest 2 con, 2 pen). HT: 17-12 Wairarapa Bush.
West Coast 24 (Nik Cumming, Amenatave Tukana, Brad Tauwhare, David Crouchley tries; Cumming 2 con) bt Thames Valley 17 (Tyrone Keith try, Penalty; Chris Doak con; Jarrod Goodall pen). HT: 14-14.
Horowhenua Kapita 15 (James So'oialo 5 pen) bt Wanganui 8 (Jona Sawailau try; Nick Harding pen). HT: 8-3 Wanganui.