Dunedin Technical was beaten 3-2 as it hosted Queenstown at Tahuna Park while Caversham scored late to edge out Green Island, 2-1.
Following the poor recent weather, the ground conditions were appalling.
Queenstown coach Jamie Whitmarsh made changes to his formation to combat Technical's direct approach and Carlos Herrmann for Queenstown narrowly shot wide in the 10th minute.
He made amends soon afterwards by scoring from a tight angle.
A Queenstown foul on the edge of the penalty box gave Technical a free kick.
The resulting shot was superbly struck by Mike Neaversen and Tech drew level.
Queenstown replied with a great ball from Rian Norton to Callum Flaws, who calmly laid it back to Hermann, who slotted the ball into the corner of the goal to give his side a 2-1 lead.
Seven minutes later, Hermann got his first half hat-trick and Queenstown had a 3-1 halftime lead.
Technical started well in the second half and replied to narrow the deficit to one.
Caversham played Green Island at Tonga Park and again the ground conditions meant both teams were unable to play to their full potential.
The game was very finely balanced. Caversham dominated possession in the first half and created five good opportunities to score.
However, Andy Ridden, Michael Hogan and Ryan Fleming were not able to finish.
Green Island had chances to take the lead but shots by Cam Scott and Max Johnston were straight at the keeper.
The score remained 0-0 halftime.
Green Island struck first in the second half when Max Johnston was taken down by Caversham keeper Liam Little in the 50th minute and a penalty was given.
Johnston calmly slotted home the penalty.
Caversham then introduced Craig Ferguson after a long injury layoff. His pace gave Caversham more space on the left-hand flank and Ben Wade found himself unmarked at the far post.
He headed back across the goal for Michael Hogan to equalise on 70 minutes.
With time nearly up and both sides creating pressure, a shot from Caversham's Jared Groves in a goal-mouth melee trickled through the mud and crossed the line for a 2-1 lead.
In the last few seconds Max Johnston's glancing header off a Tom Milton free kick was only centimetres away from forcing extra time but was not enough to stop Caversham taking the win.
Both Caversham and Queenstown now go forward to the last 16 draw.
In the Southern Premier League, Mosgiel and Northern had a 1-1 draw.
In the women's knockout cup, Mikayla Gray scored twice to help Dunedin Technical to a 3-0 win over Roslyn-Wakari.
-By Neville Watson
