The black-and-reds looked the better side for long periods in the first round at Tauranga Domain before being whistled off the park in the second half.
"We definitely addressed it on Tuesday," captain Doug Edwards said of the need for his side to be squeaky clean.
"There were some parts that we couldn't really control but we are going to control what we can to get that penalty count down."
Former Southland player Shane McDermott has been given the appointment for what shapes as a potential classic.
Whakarewarewa's narrow low-scoring win over Mount Maunganui in the final round of the regular season resembled trench warfare, but both teams will be hoping for a dry track come Saturday.
"There's a few bruised and battered boys after the weekend but I think the intensity and motivation is there for a semifinal," Edwards said.
"It was a fitting last round-robin game to win that one and go through.
"Everyone is on board this week, all that middle-of-the-season injury list is just starting to come right so, hopefully, we'll have everyone fit and healthy on Saturday.
"It's a do-or-die match basically, the good thing is it's a semifinal and a game that needs to be won and I think that's in our favour.
"We haven't beaten them this year but we are looking forward to it."
