University A held on to the Jonathan Keogh Memorial trophy with an impressive 28-20 win against Dunedin.
The defending champion had too much strike power in the backs for Dunedin and chalked up its 10th consecutive win.
Harbour remains in second place on the competition standings after a 34-19 win against Alhambra-Union.
Its lack of discipline proved costly, though. Halfback Tala Fagasoaia was sent off for punching.
Kaikorai moved into third place with its 38-17 win against Green Island.
Southern prevailed 29-13 against Taieri but remains outside the top four, while Zingari-Richmond thrashed Pirates 64-27 in the battle for the wooden spoon.
University A 28
Dunedin 20
No other team in the competition can conjure up tries quite like University A.
Its match with Dunedin at Kettle Park was still in the balance when the defending champion produced a simple, yet effective, set piece move which ended with Fletcher Smith dotting down part way through the second spell.
From a scrum on halfway, the classy first five-eighth received the ball and swung away a wonderful skip pass to impressive winger Gavin Stark to run on to.
He was basically on the outside of his opponent when he pulled the ball in and he scampered down the right flank.
He passed inside to a support player and then Smith was on hand to take the final pass.
Rugby looks so simple when players execute that well.
University had scored three first-half tries but Dunedin scored either side of the break to set up what promised to be a tight finish.
Arguably the home side had the better of the forward exchanges.
Prop Donald Brighouse crashed over shortly before the break and powerful loosie Hame Toma scored not long after the restart, to close the gap to 18-13.
A high tackle on Faasiu Fuitai helped University release the pressure with a Stephen Fenemor penalty.
Dunedin infringed at the restart and then Smith scored that fabulous try which he set up with that cracking pass.
Gareth Evans bashed his way to the line to score a consolation try for Dunedin right on fulltime.
Zingari-Richmond 64
Pirates 27
Zingari-Richmond ran in 10 tries to thump a hapless Pirates side which has now conceded 50 points or more in each of its last five games.
The Colours were on the front foot at Hancock Park. They led 33-10 at halftime and dominated up front.
Former Otago Nugget Tom Rowe produced a commanding performance in the lineouts, while loose forwards Chris Bell and Lafaele Faamoe made good ground when they carried the ball.
Their work set a sturdy platform for halfback Maurice Stone and first five-eighth Thomas Johnson to work their magic, while veteran midfielder Neil Brew hit the ball up hard.
Winger Inoke Naivalulevu capitalised on the good work done inside, scoring three tries.
He is probably one of the smaller premier rugby players but used his speed and eye for a gap to finish off superbly.
Pirates had their moments.
The home side strung together its best passages of play before and after the break.
They also picked up a four-try bonus point to take something away from the game.
Hooker Hamish Boult had a strong game. Centre Kieran Fowler defended well and was by far Pirates' best back.
Southern 29
Taieri 13
It took more than an hour for the game to bust open, but Southern ran out convincing victors in a torrid encounter at Bathgate Park.
With three-quarters of the game gone, only an exchange of penalty kicks at goal kept Southern ahead on the scoreboard, as committed defence from both sides had play drifting between the 22m marks.
First five-eighth Josh Casey made a welcome return to the Taieri ranks and his option-taking and kicking ability provided fuel for the Taieri attack.
With time ticking down in the final quarter, a 40m break from Southern prop Mike Mata'afa split the Taieri attack and the game wide open.
Mata'afa's turn of speed into the gap was ended just short of the line, but on hand for the offload and try was lock Axel Hohneck.
In an action replay, Southern halfback Josh Walden ran 60m up Mata'afa's track in mid-field, resulting in brother Tei offloading a pass to wing Jono Hayes to finish the movement off with a try in the corner.
Taieri was down, but definitely not out, as it regrouped, pinning Southern in its own half and eventually getting width and space for wing Glen Beadle to score.
But as Taieri desperately sought a bonus point, Southern had the final say, when flanker Ryan Thompson ran in a try from 25m out.
Kaikorai 38
Green Island 17
Kaikorai weathered the first half hurricane to beat Green Island 38-17 at Miller Park.
Green Island played ferocious attacking rugby in the backs and forwards in the first spell and the Kaikorai defence took a battering.
Green Island controlled the lineout and its powerful front row of Mike Bennett, Ricky Hollamby and Ross Geldenhuys pushed Kaikorai back in the scrums. Two first-half tries came from scrums.
Hollamby and loose forward Jackson Hemopo made ground with the ball. Sam Eriepa and Taisei Hayashi were dangerous in the midfield.
The Kaikorai backs took their limited chances to score two tries and led 14-12 at the break.
Green Island ran out of steam in the second spell when super subs Lachie Landels, Willie Miller and Lee Allen gave the Kaikorai forwards more grunt.
Green Island contained No8 Paul Grant in the first spell but he was dangerous with the ball in the second spell and made five clean lineout takes. He was backed by lock Blair Tweed.
The Kaikorai backs were dangerous with the ball.
Wing Eti Slater and fullback Tony Ensor created gaps and centre Danny van der Voort was solid in the midfield.
With fast-running from the backs and the quick recycling by the loose forwards, Kaikorai added four tries and 24 points in the second spell.
Harbour 34
Alhambra-Union 19
Harbour was reduced to 14 men early in the second spell but escaped the North Ground with a reasonably comfortable win against Alhambra-Union.
Harbour led 26-14 at the break but halfback Tala Fagasoaia was sent off for punching about three minutes into the half.
While down a man, the Hawks still had too much grunt in the pack for Alhambra-Union.
Lock Ben Whale and front rowers Sekonaia Pole and Aiden Spence had a big impact on the tight exchanges, while former Highlander Seilala Mapusua turned back the clock with a strong performance in the midfield.
Fullback Logan Allen made some decisive runs and kicked well and was probably the best back on display.
Loosie Iloa Lihau scored two tries, including the opening try.
Alhambra-Union fluffed a clearance kick and Harbour swung on to attack.
Lihau crashed over following several drives at the line.
Alhambra-Union's ball handling was poor and its tactical appreciation not much better.
Flanker Jacob Coghlan was one of the best for the home side.
He sprang into action when Harbour threw the ball over the back of the lineout.
He grabbed it and scored and had a pretty industrious game.
Outside back Poasa Cama looked threatening when he got opportunities, and Adam Simpson showed some good pace on the left wing.
