One of them will miss out on a spot in the semifinals and it could come down to a bonus point or two.
Kaikorai has the points on the board. It is in third place with 52 points but is playing University A and, on all available evidence, will probably lose.
Southern is in fifth spot with 48 points and will need to beat Green Island if it is going to have a chance of reaching the semifinals.
The smart money is on the Magpies winning that encounter which will lift their total to 52 points, or 53 points if they score a fourth try.
That will put the heat on Kaikorai. It lost both round-robin matches to Southern, so if both teams are level at the end of the round it will be Southern that progresses.
That means if Kaikorai cannot beat University, it will likely need a bonus point or two to reach the playoffs for the first time since 2010.
Kaikorai will be without powerful No 8 Paul Grant who is sidelined with calf injury, while Southern will be without talented first five-eighth Josh Ioane, who is heading home for the weekend to celebrate his 21st birthday.
University A has set the benchmark this season and, with 14 wins from 15 games, has a comfortable 14-point buffer at the top of the competition standings.
Harbour is in second place with 55 points and is safely through to the playoffs.
But it can slip to fourth place if it loses to Taieri at Watson Park and Kaikorai and Dunedin both win.
You can bank on Dunedin winning.
It plays Pirates at Hancock Park and a bonus point win will lift its points total to 57.
At the end of the round-robin the competition will split into a top four, middle four and bottom two.
Pirates have easily secured a spot in the wooden spoon match with just one win in 15 games.
The team is conceding 58.06 points a game while scoring an average of 15.86.
Either Zingari-Richmond or Alhambra-Union will join them in the fixture.
The teams play at Montecillo today and will both be chasing a fourth win for the season.
Last year's beaten finalist, Taieri, made a strong start but fell away and the best the Eels can hope for is to win the middle four.
The format for the middle four will see the fifth-ranked side hosting the eighth-ranked team while sixth will play the seventh in the other match.
