Only eight points separate second-placed Alhambra-Union on 34 points and eighth-placed Harbour on 26.
The top four at the moment are University A 46, Alhambra-Union 34, Pirates 33 and Kaikorai 32.
But Southern, Dunedin, Taieri and Harbour are still in touch with three rounds of the Gallaway Trophy left.
Kaikorai, which beat Dunedin 29-25, has won its past three games and has been the big mover.
University A regained the Cavanagh Trophy when it beat arch rival Southern 25-20, and Alhambra-Union scored two tries in the last three minutes to beat Pirates 29-26.
Flanker Eben Joubert scored a second-half try to help Harbour beat Taieri 16-11 and lift the Speight's Challenge Shield.
Classy midfielder Andrew Parata showed some of his best form as University A regained the Cavanagh Memorial Trophy against tenacious Southern at Bathgate Park.
Southern took an early 13-0 lead, University A stormed back to be ahead 22-13 at halftime, and it was a war of attrition in the second spell with the students unable to capitalise on their dominance of territory and possession.
Southern came back within range when centre Joe Hill scored nine minutes from the end and, with No 8 Paul Grant in the sin bin, University A had to defend stoutly in the closing stages.
This was a match University A should have won more comfortably but that was not the fault of Parata, who was the playmaker at second five-eighth.
He constantly probed the line, linked well with his outsides and set up the third try with a break, kick and chase which finished with hooker Simon Forrest scoring.
Tom Halse also impressed at first five-eighth and scored 15 points through a solo try, when he burst 30m through the defence, and four goals from five attempts.
Grant was always a threat from No 8 and the twin towers, locks Alby Herron and Josh Townsend, featured in the lineouts and general play.
It was a plucky display by Southern, which hung tough despite looking the second-best side for long periods.
Winger Greg Zampach showed strength, speed and determination to score his try, Luke Herden featured in the build-up to both tries and Simon Knight, Uili Koloofai and captain Warren Moffat were the pick of a competitive pack.
University A 25 (Tom Halse, Paul Grant, Simon Forest tries; Halse 2 pen, 2 con), Southern 20 (Greg Zampach, Joe Hill tries; Lewis Hancock 2 pen, 2 con).
Halftime: University 22-13.
Referee: Ross Barnett.
Alhambra-Union left its best for last and came from behind to score two long-range tries to beat Pirates at Hancock Park.
Pirates appeared to have the game sewn up when first five-eighth Glenn Dickson charged down an attempted drop goal by Alhambra-Union captain Luke Reihana with only five minutes left.
He dashed 80m and centre Marshall Suckling was up in support to score his second try and Pirates led 26-17.
Alhambra-Union then moved into top gear, counter-attacked from its own 22m and spread the ball wide.
Prop Ben Pereira scored a try with just one minute left.
Alhambra-Union attacked again from the kick-off and flanker Brad Rapley dashed 22m to score the winning try in the corner.
Suckling scored a brilliant first-half try for Pirates when he ran untouched for 60m, and Dickson's kicking deserved to win the game for Pirates.
His line kicking kept Alhambra-Union on the back foot and he kicked four goals from eight attempts in difficult wind conditions.
The Pirates scrum had the edge, with props Shane Parata and Daniel Johnson having strong games, and Pirates gained better ball in the lineout, with lock Nic Wilson making five clean takes and being backed up by Josh Clark.
Jarid Bradley was the best of the Alhambra-Union backs and flanker Brad Rapley and prop Pereira the best of the forwards.
Alhambra-Union 29 (Luke Reihana, Jarid Bradley, Brad Rapley, Tom Viggo, Ben Pereira tries; Reihana 2 con), Pirates 26 (Reopoamo Aillilo, Marshall Suckling 2 tries; Glenn Dickson 3 pen, con).
Halftime: Pirates 13-10.
Referee: Todd Pullar.
Strong defence pressured Dunedin into errors and gained Kaikorai an upset win against last year's champion at Kettle Park.
Dunedin looked to have the game in the bag when it played with the wind in the second spell with the scores level, 15-15, at the break.
Dunedin camped inside the Kaikorai 22m for much of the second spell but could only score one try because of strong defence by the Kaikorai forwards and pressure from the backs.
When No 8 Joe Dobson scored after seven minutes, Dunedin led 22-15 and had the game in its grasp because it had the advantage of a 10-point wind.
Dunedin appeared to have the game in control until breakouts after 30 and 38 minutes led to tries by lock Noa Soqeta and No 8 Kensak Palepoi and gave Kaikorai a narrow win.
First five-eighth Cam Rutherford kicked accurately and controlled play efficiently and was the best of the Kaikorai backs.
Wing Richard Cowley had the spark that led to the two breakouts while Soqeta, Palepoi and flanker Lee Allan played well in the forwards.
Halfback Robbie Smith was the only Dunedin back to end the game with credit but forwards Gareth Evans, Andrew Mackintosh, Richard Thompson and Will Henry had rugged games in the pack.
Kaikorai 29 (Mark McGregor, Cam Rutherford, Kensak Palepoi, Noa Soqeta tries; Rutherford pen, 3 con), Dunedin 25 (Joe Bradley, Joe Dobson, Gareth Evans, Richard Thompson tries; Robbie Smith pen, con).
Halftime: 15-15.
Referee: Tim Baker.
The game was over for Zingari-Richmond after Green Island scored its first try and took complete domination of the game at Miller Park.
Green Island scored three tries in the first spell to lead 24-3 at the break and had the bonus point when fullback Albert Alapati scored his second try early in the second spell.
Green Island went off the boil in the last 15 minutes and Zingari was able to come back into the game and fullback Nathan Napier scored the team's only try.
Prop Andre Clarke was a strong scrummager and made ground with the pick and go.
Green Island flankers Jason Bint and Josh Beer were quick to the breakdown and linked efficiently with the backline.
Winger Mika Mafi was always dangerous with the ball in hand and centre Chris O'Neill and Alapati had attacking flair in the backs.
No 8 and captain Chris Bell worked hard all day and was the best of the Zingari forwards.
He was backed by lock Brady Carmichael, while halfback Troy England was the best of the backs.
Green Island 41 (Albert Alapati 2, Chris O'Neill, Mika Mafi, Jason Bint tries; Alex Davies 2 pen, 5 con), Zingari-Richmond 13 (Nathan Napier try; Mark Hunter 2 pen, con).
Halftime: Green Island 24-6.
Referee: Adam Morrison.
In a game that promised much but delivered very little, Harbour departed Peter Johnstone Park with a narrow win and the Speight's Challenge Shield.
Taieri started well through an early try to Tom Davie, but Harbour muscled its way back into the match through its forward pack, with Peter Mirrielees and Eben Joubert making their mark with the pick and go.
In the backs, Ben Marshall, George Folau and Jonnie Hughes were solid in defence and posed a threat on attack.
Both Harbour's tries came in the final quarter as mistakes crept into Taieri's game and Harbour was able to gain some ascendancy.
Taieri was again well led by inspirational captain and No 8 Charlie O'Connell.
Locks Kurt Webster and Steve Green along with halfback Carne Parata stood out in broken play but were often let down by a high error rate from support players.
Harbour 16 (Craig Sneddon, Eben Joubert tries; Sneddon 2 pen), Taieri 11 (Tom Davie try; Andrew Reid 2 pen).
Halftime: Taieri 8-3.
Referee: Jeff Grubb.
