Northern put the setback of missing a seventh-minute penalty behind them to create most of the game's chances and finally went ahead a minute from halftime.
Defender Caitlin Smallfield drove into the penalty box and crossed for Hannah Hoeksema to open the scoring with a superb finish. Player of the Day Hoeksema secured the win in the 58th minute, grabbing her second goal after Capital failed to clear the ball as it pinged around the penalty box. Acott said he was happy with how Northern performed considering they did not know too much about those opposition.
"We were a little bit in the dark as to how we would set up, but we decided in first few minutes to be positive," Acott said. "They took us by surprise and were very good, especially through the midfield."
In the earlier game at Fred Taylor Park, the Northern Development Team went down 4-1 to a New Zealand under-17s team.
Defending champions Northern will play Auckland in the final on Sunday at Fred Taylor Park in Whenuapai.