"It's a huge game for them, it's their chance to show they can foot it with the big boys," Keinzley said.
"It could be the making of them."
Wairarapa United will be without four of their regular players. Striker Seule Soromon is sidelined with a hamstring injury, utility Brian Kalteck is on a one-match suspension (not Waisake Sabatu as reported yesterday) and the two Frenchmen Alssney Cissoko and Charles Mallman have returned home.
Regular goalkeeper, the in-form Matt Borren, will be between the sticks for Wairarapa United and Carl Shailer, Adam Cowan, Sabatu and Josh Margetts will start in defence. In midfield will be Nathan Cooksley, Miroslav Tvaroh, Tapp and Hemi, and up front Dale Higham and Aaron Spierling.
Keinzley concedes Olympic will be favourites but isn't giving up on the possibility of his side recording an upset win.
"It's all about us competing strongly early on and putting doubts in their minds.
"Do that and you never know what might happen," he said.
For the Wairarapa United seconds a win or a draw in their Capital third division match with relegation-threatened Wainuiomata at Howard Booth Park, Carterton, on Sunday will be enough to make them third division champions for 2013.