The top six teams in the Dunedin division 1 competition all play each other this week.
The Harbour and Green Island fixture at Watson Park shapes as the game of the round.
The Hawks are the only unbeaten team remaining, and are in third place with 14 points.
They had a bye in the opening week before starting with a tense 35-31 win over Southern.
They dispatched Zingari-Richmond 41-12 in round three and edged past Taieri 15-13 at Peter Johnstone Park before the Easter break.
First five Rique Miln landed five penalties in a clutch effort from the kicking tee.
Green Island (first place, 15 points) emerge as their greatest challenge so far.
The defending champions lost in their last outing. They stumbled against their bogey team, losing 44-26 to University.
The Grizzlies had set the benchmark but were unable to recover from a poor start. They conceded 17 points in eight minutes.
Southern (fourth, 12 points) have a home fixture against Taieri (second, 15) in another opportunity to see how the top teams are shaping in comparison to each other.
Taieri outscored the Hawks two tries to none, but missed a late penalty that would have secured the win on Thursday night.
The Eels are well organised and well coached. They squeaked past University in a thriller in round three.
It took a fair degree of character to rally in the topsy-turvy game which looked like it may have slipped away.
Southern started their campaign strongly with a comprehensive 50-27 win over University. They were edged out by Harbour in round two and finished over the top of Zingari-Richmond in round four.
They have a team built around a hard-working forward pack and an experienced backline.
University (fifth, 12 points) will host Dunedin in another game that is hard to pick.
Dunedin (sixth, 7) made the final last season and had several opportunities to win it.
They have retained the bulk of that squad and should be up there again. But they have made a slow start with back-to-back losses.
They posted a 59-5 win over struggling Alhambra-Union in round four, but University will present a sterner challenge.
If Dunedin lose tomorrow, they could potentially drop out of the top six.
Zingari-Richmond (seventh, 7 points) have a bye but Kaikorai (eighth, 5) have an opportunity to move up with a win over winless Alhambra-Union (ninth, 0).
