"This is an important game against a Maori club steeped in history so we need to step up our game and make sure our defence is well drilled.
"In the last match we just held on. We were ahead towards the end, and should have pushed on to get another try but instead we let them back into the game and were lucky to get a result.
"We really need to drive the nail into the coffin when we get the chance because against stronger sides we will be made to pay."
Currently Whaka are eighth in the table on 17 points but are just two points behind local rivals Rotoiti and five behind their opponents this weekend.
The side has been strengthened by the return of fullback Ryubyn Vaipo who has significantly impacted the back line.
Rangataua come into the game on the back of a 26-25 loss at home to ninth placed Greerton Marist - after winning their previous three matches.
"We want to be competing with the top five in the division and be in touching distance of that pack," said Irihei. "Now we are really fighting and have to get a good start in the game. And this week I do not want to see us letting tries in."
Meanwhile, Rotoiti will look to win their fourth game on the bounce as they host third-from-bottom Arataki at home.
"On paper it looks like it should be another good result for us," said Rotoiti coach Dave McLean.
"But they are desperate for points and despite losing against Whaka they put in a gutsy performance so we have to be on the top of our game."
