Wins were recorded on Saturday by University, Taieri and Harbour - who are all now safely into the top four - while Green Island also beat Zingari-Richmond at Montecillo.
Kaikorai and Southern are on 46 points with one round left. Should they finish on the same number of points it will be decided on points differential, which favours Kaikorai. Southern plays Alhambra-Union and Kaikorai plays Harbour next week.
University 19
Southern 17
There was not much between the sides in an intriguing clash for the V G Cavanagh Memorial at the University of Otago Oval, with University eventually prevailing 19-17.
University created plenty of chances, but some tigerish Southern defence and a lack of finish by the University players led to a close 80 minutes.
Southern went ahead with just over 10 minutes left when fullback Mackenzie Haugh burrowed over after Southern attacked the line.
Haugh kicked the conversion to put his side 17-14 ahead. But University muscled up in the forwards and when the ball went wide fullback Taylor Haugh, who had a quiet match, found some space and gave winger Gavin Stark some room.
Stark put on the afterburners and scored to put University ahead.
Southern had a chance near the end, but the students' power scrum twice pushed it off the ball.
University flanker Sam Dickson was an abrasive figure in the match and never backed down, while locks Ben Reidy and Josh Hill were industrious. Halfback Connor McLeod threw out some accurate passes and first five-eighth Mike Williams kicked well when needed.
Southern skipper Kyle Harris scored a nice try and was busy, while prop Mike Mata'afa made metres with the ball in hand.
Green Island 45
Zingari-Richmond 22
Green Island pulled away in the second half, helped by a couple of penalty tries, in a fiery match at Montecillo.
The home team had put on a decent display in the first half and trailed just 14-12 at the break. The Zingari-Richmond forwards hunted well as a pack and were energetic at the breakdown.
But the Green Island forward pack has made big advances this season, and came into its own in the second 40 minutes.
It won a penalty try early on in the second half through its powerful scrum and pulled away, as the home team could not get any possession.
Zingari-Richmond skipper and first five-eighth Thomas Johnson was shown a red card just before the midway mark in the second half for a high tackle and also getting involved in a melee afterwards.
The game degenerated through the second half as discipline from both teams dropped and there was a high error rate.
The Green Island pack worked well as a unit and eventually won the battle of their opposites.
Hooker Jake-Lane Fowler was busy for Green Island, as was his front row colleague Peter Mirrielees, while lock Jared Williams got round the field.
Zingari-Richmond tried hard in the second half when one man down and managed to score some points. Lock Matt McCormick put in another good effort.
Midfield back Keenan Masina scored a couple of tries and broke the line most times he received the ball for the home team.
Taieri 27
Alhambra-Union 19
It was a game of two halves at Peter Johnstone Park.
Taieri came out well and led 24-7 at the break, and seemed to have the game well under control.
But it went to sleep in the second half and could only grab three points for all its efforts in the second stanza.
Alhambra-Union played better in the second half and got handy enough, but went down 27-19.
Right at the end it had a chance to score again to at least get a bonus point, but as it had been for most of the match, its lineout was not good enough, and it coughed up the ball.
The Taieri set piece was in command for much of the game. Its scrum was dominant and denied much of the ball to the visiting side.
The Taieri tight five got into its work, while openside flanker Josh Brown was all round the paddock and worked hard.
Taieri found some enterprise it its midfield and created some chances for the outside men, with Mitchell Scott scoring a try and looking dangerous.
Alhambra-Union No 8 Connor van Turnout had a top match and was rewarded with two tries for his ability to get round the paddock.
Sevens star Vilimoni Koroi started at first five-eighth for Alhambra-Union before moving to fullback. He set up one try with a nice turn of pace and proved a handful for the Taieri defence.
Harbour 52
Dunedin 3
Dunedin's Jekyll and Hyde season continues with an utter capitulation to a rampant Harbour side out at Kettle Park.
Harbour racked up five tries in the first spell as the Dunedin backline concluded tackling was not an option. All the tries were a result of glaring missed tackles, and this was exemplified in the third try to Logan Allen, who waltzed through five to wander across and score.
Not surprisingly Harbour dominated territory and possession through its monstrous pack. On the few occasions Dunedin had the ball and field position, they coughed up ball through forward passes and loose carries.
In the second spell they gave up numerous intercept passes, and Harbour was good enough to score from two of these. Harbour has been Dunedin's nemesis this year, as they have racked over a century in points against the Sharks in their two games.
Up front, locks Sione Misiloi and Joketani Koroi were powerful on the carry, and both ate up big metres with ball in hand and were efficient at lineout time. Naulia Dawai at blindside was menacing every time he touched the ball.
Logan Allen directed traffic well, and Sio Tomkinson was a class act in the midfield, scoring two tries and setting up two others with his great passing skills.
For Dunedin, loosies Morgan Reedy and Daniel Hogan did their best to plug the numerous holes, and midfielder Isaiah Duncanson at least attempted to tackle and made their only breaks out wide.
Harbour had to win this game, as they now unfortunately lose 6 players to the Otago team, and will struggle to beat Kaikorai next week. The win sees them finish third, and they will play Taieri in the semi finals in two weeks time.