Mant added that the Sharks really turned up the heat in the physical match-up and attacked channels close to the ruck.
Matt Matich showed his off-season stint with the Northland and Auckland sevens teams had helped his game as he was a menace on defence, forcing Otamatea to commit numbers to the ruck to protect their ball.
Mant noted the influence of young 18-year-old second-five Taisyn Williams, who scored Otamatea's only try in his first premier grade match, and halfback Wheriko Tawhiri, also 18.
"[Tawhiri] had a strong game and linked well with our 10, John-Luke Whitehead.
"Shane Neville was another who played well. He played through injury and still caught the eyes of [Northland assistant coach] Derren Witcombe."
The Sharks and Otamatea match was the last game of the weekend after the remaining teams played on Thursday due to the Easter break.