Baden Kerr kicked a last-minute penalty to see Counties Manukau snatch a 31-30 win over Bay of Plenty in Rotorua on Sunday.
The result means the Ranfurly Shield holders have now all but secured a Premiership play-off place. By contrast, relegation now seems unavoidable for Bay of Plenty.
In a ding-dong battle, the sides scored three tries apiece and BoP looked to have secured the result when prop Kane Hames crashed over with just four minutes to go, only for Kerr to break the Steamers' hearts with the last kick of the game.
Counties led 15-10 at the interval but were being destroyed at scrum time and had no answer to the BoP rolling maul.
The Steelers had charged into an early 12-0 lead, via tries from Maama Vaipulu and Frtiz Lee, but the home side stayed in touch thanks to try from Queensland Reds Beau Robinson - from a rolling maul - and the accurate boot of Willie Ripia.
After the break, the Steamers forward domination continued with another try coming from a rolling maul for Nathan Harris to take the lead. But Counties replied via a power try from Hika Elliot from close range.
It was off another dominant scrum that Hames pounced on the loose ball to score. With the scores locked at 28-28, fly-half Willie Ripia maintained his perfect record from the tee with what looked like the winning conversion for BoP.
But the Steamers would pay dearly for their inability to seal the deal, as Counties won a break-down penalty and Kerr split the uprights in a dramatic finish.
For Bay of Plenty:
Tries: Hames, Harris, Robinson
Cons: Ripia 3
Pens: Ripia 3
For Counties Manukau:
Tries: Elliot, Lee, Vaipulu
Cons: Kerr 2
Pens: Kerr 4
Bay of Plenty: 15 Elliot Hagan, 14 Maritino Nemani, 13 Kendrick Lynn, 12 Nick Evemy, 11 Kimami Sitauti, 10 Willie Ripia, 9 Samisoni Fisilau, 8 Carl Axtens, 7 Beau Robinson, 6 Joe Tupe, 5 Culum Retallick, 4 Josh Sole, 3 Pingi Talaapitaga, 2 Nathan Harris, 1 Kane Hames.
Replacements: 16 Kalem Chan Boon, 17 Joe Royal, 18 Johan Bardoul, 19 Kieran Black, 20 Josh Hall, 21 Sam Beard, 22 Junior Va'a Tofa.
Counties Manukau: 15 Sherwin Stowers, 14 Ahsee Tuala, 13 Reynold Lee-Lo, 12 Bundee Aki, 11 Toni Pulu, 10 Baden Kerr, 9 Kane Hancy, 8 Fritz Lee, 7 Maama Vaipulu, 6 Adam Cathcart, 5 Jimmy Tupou, 4 Ronald Raaymakers, 3 Jarrod Firth, 2 Hikawera Elliot, 1 Simon Lemalu.
Replacements: 16 Suli Taufalele, 17 Sam Aiono, 18 Sikeli Nabou, 19 Mark Selwyn, 20 Lucky Palamo, 21 Ki Anufe, 22 Sam Vaka