Green Island, though, will have to do the business without key No8 Dylan Nel, who has been ruled out with injury.
Harbour led the competition for part of the season but ended up being passed by University and Taieri in the run home.
As the third-placed team, it will face University at the University of Otago Oval tomorrow afternoon.
Taieri hosts Green Island at Peter Johnstone Park.
Green Island is back in the playoffs for the first time since 2002 but coach Dean Moeahu said the side was not resting on its laurels.
"We are ticking along all right and the boys are excited to be in the semifinal. They'll be willing and have plenty of energy for the game. We have talked about it and about putting on the best performance that we can," Moeahu said.
"We have not beaten Taieri in 10 years. I think the last time we beat them was when Bender [Ben Smith] was involved.
"We've had a draw against them. This year had a one-point loss, had a four-point loss in the second game."
Moeahu said the onus was on top qualifier Taieri, which has home advantage, to keep its 10-year unbeaten record.
Green Island takes the approach, as do many teams, to just play as well as it can and to put on its best possible performance.
It will have to do without impressive youngsters in hooker Jake Fowler (shoulder) and loose forward Sean Jansen (head), who are out with injury.
Nel suffered a slight injury while training with Otago this week and has been declared off-limits by Otago.
Although disappointed Nel will miss such a big game, Moeahu said Green Island had played plenty of games this year without him so should be able to cope.
Harbour had last weekend off with the bye and coach Ryan Nicholas said the team had rested some tired bodies.
Many travelled to Wanaka to watch the Ranfurly Shield match.
The side has everyone available and, importantly, will welcome back Logan Allen from a dislocated shoulder injury.
He went off when University defeated Harbour 53-0 just over a month ago on the same ground the semifinal will be played tomorrow.
Nicholas said the loss of first five-eighth Allen that day told as it was forced to change things around and defensive combinations went missing.
But that game would have no bearing on tomorrow's match, and there was no talk, either, of last year's final which ended in a draw after extra time.
"Logan being back will give us more direction and will better execute his game plan. He can put us in good positions where we can play to our strengths," Nicholas said.
Harbour is back to full strength, Nicholas said.
University has won both games between the sides this year.
After a glorious season weather-wise, rain is forecast for tomorrow and that is always a leveller.