Saturday's game would determine the gap between a division two and a premier side, he added.
Waipu was relegated to division two about five years ago and since then Reader said the team had been rebuilding with the aim of getting back into the premiers.
"Otamatea had a good season, they've had some close games, scored some points but leaked some as well and our strength is speed and mobility.
"We are the smallest team in division two, we've got a good forward pack and a technically sound set piece but we know we're in for a tough game."
Waipu has lost only four games in two years. At the weekend it scored two tries, two conversions and four penalties while Whangaruru managed two tries.