Kaikorai set up the platform for its 25-16 win with a massive effort in the scrum, while Alhambra-Union sealed its dramatic 25-24 win through a try in the final moments to halfback Caleb Gray.
Taieri defeated Zingari-Richmond 29-15 and Southern remains unbeaten after posting a 38-20 win against Green Island.
Kaikorai: 25
University: 16
The game is won up front, so they say.
It certainly proved that way at the University Oval.
Kaikorai built its surprise 25-16 win against University with a devastating effort by the front row.
None were better than prop Jonah Aoina. He bagged two tries and had an instrumental role in the other.
He had very solid support from Highlanders back-up hooker Adrian Smith and fellow prop George Hendry. And the trio got their first real opportunity to impresses with about 10 minutes remaining in the opening spell.
University led 8-3 thanks to a Taylor Haugh penalty and a try to No 8 Adrian Fou. But Kaikorai put in a big shove from a 5m scrum and would have scored had University not infringed.
The referee awarded a penalty try and it signalled a turning point in the match.
Shortly after, Kaikoria drove deep into University territory through a run from second five-eighth Kieran Fowler and Aoina barged his way over from a quick tap.
Ben Miller drilled a penalty to extend the lead to 20-8. Kaikorai added its final points with a try just before halftime and it was a cracker.
University fullback Sam Aitken had sliced through but the ball was turned over and Kaikorai counterattacked from 70m out.
Winger Matt Jones made the initial break. Then the ball was swung right where Miller carried strongly. Aoina stayed in support and brushed off the last tackle to score.
University spent a lot of time camped in Kaikorai's half in the second stanza but only had a penalty to show for it until Aitken scored in the final minute of the match to reduce the margin.
Alhambra-Union: 25
Harbour: 24
The home team finally got its hands on the Ross Godman Rooster (trophy) which was instituted three years ago to commemorate one of their stalwarts. Harbour won the first two encounters for the Rooster. But it was a close run thing with halfback and captain Caleb Gray scoring the winning try in the last play of the game.
The first half was a mistake-ridden affair and neither side had any real domination. Zach Porter put AU in front with an early penalty. It was not until the 26th minute that the first try arrived. The big Harbour pack threatened inside the 22 and burly lock Chucky Koroi crashed over.
Right on halftime, Alhambra-Union replied in kind when prop Harley Iraia crashed over close to the posts to take a three-point lead into the break.
Early in the second spell, Caleb Gray intercepted a loose Sala Halaleva pass and trudged 45m to give his side a handy 10 point lead. Halaleva made amends after 18 minutes when he scored off a slashing Sio Tomkinson break to drag the lead back to three. Zach Porter kicked another penalty to give Alhambra-Union a six-point lead with 12 minutes to play.
Harbour finally woke up and its big pack on the back of some powerful surges scored two quick unconverted tries to give it a four-point lead with seconds to go and the game looked in the bag. But Tomkinson and Allan had missed kicks from in front and these misses proved expensive.
The home side stormed back into the 22 and with time up on the clock Gray spotted a hole through the ruck and dived over to score the winning try much to the jubilation of their Alhambra-Union supporters.
Gray with his tidy clearance and two tries was probably their best. Poasa Cama looked dangerous at times in the midfield. But its loose forwards Ty Pelasio, in his 50th game, Jacob Couglan and Max Aitkenhead were prominent throughout and lock Hayden Fluery was into everything.
For Harbour, George Bower, Sione Misiloi, Koroi and Ben Whale were powerful on the carry and Tomkinson was probably the side's best back.
Taieri: 29
Zingari-Richmond: 15
Wing Glen Beadle scored two quick tries in the middle of the first spell to give Taieri the advantage at Peter Johnstone Park.
The first try came after 17 minutes when he came into the line at speed after a scrum inside the Zingari 22m.
The second came three minutes later, when he grabbed the ball after a tactical kick to the corner by first five-eighth Josh Casey.
The powerful Zingari pack had dominated the first 15 minutes and came close to scoring on two occasions with driving forward rushes.
They dominated the lineout and flanker Tom Rowe and lock Eli Tonga both made five clean takes.
Taieri held a 14-3 advantage at the break and stretched the margin by another seven points early in the second spell, when Casey scored after a jinky 15m run after a scrum inside the Zingari 22m.
The game lost its shape after this and three soft tries were scored in the final 10 minutes.
The Zingari pack always had the edge with No 8 Chris Bell, in his 219th premier match for the club, hooker Karl Still and flanker Jack Wolfreys having solid games.
Taieri fullback Mitchell Scott used his speed to score Taieri's fourth try and was dangerous on the counterattack, and second five-eighth Kori Rupene was steady in his 100th premier game for the club. Accurate passing by halfback Ryan Hammer gave the Taieri backs space.
Southern: 38
Green Island: 20
A second-quarter, three-try scoring blitz by Southern No 8 Mika Mafi set his side up for victory in a highly competitive match at Bathgate Park.
With a try apiece, and the scores locked up at 5-5 after 22min, a clever piece of play from Southern left wing MacKenzie Haugh led to Mafi's first try.
Haugh, who earlier scored to open Southern's account, appeared set to reacquaint himself with the corner flag until he found himself surrounded by the Green Island cover defence.
He opted to grubber-kick through a gap and off-break a bounce and the ball fell into the hands of Mafi, who ran in the five-pointer from 10m out.
With halftime approaching, Mafi continued his one-man demolition, intercepting a pass on the Green Island 22m to run in a try under the bar. Then straight from the restart, and in referee's time before the break, he played a major role in Southern running the ball back up field, for Southern to pound away at the Green Island line.
Southern eventually gained a penalty within the shadows of the posts, and opted for the tap kick. Mafi got the ball and scored again to stretch the lead to 26-5.
First five-eighth Josh Ioane cut through the Green Island defence for a 50m run to the tryline in the opening minutes of the second spell, extending Southern's advantage to 31-5.
But Green Island regrouped and outscored the home side in the second half, replying with three tries.
But for Green Island's want of a goal-kicker, the final score line of 38-20, could well have been less flattering for Southern.
