Tasman have scored two tries in the final 10 minutes to maintain their unbeaten march through the Mitre 10 Cup premiership, booking a home final with a 18-9 semi-final win over Auckland.
The defending champions made much of the running and held the Mako to 6-6 penalties, with fulltime looming.
But lock Quinten Strange finally broke the deadlock with the game's first try, converted by Mitch Hunt, before midfielder Alex Nankivell sealed the result with another two minutes from the end.
While Auckland were ultimately restricted to three penalty goals from first-five Harry Plummer, they so nearly broke the game open with 20 minutes remaining, when Tumua Manus appeared to score a spectacular try.
Wing Salesi Rayassi recieved the ball on the end of the backline and put a delicate kick through for Manu to gather and cross the tryline.
Replays suggested the ball may have clipped the touchline from Rayassi's boot and the try was disallowed.
Tasman 18 (Strange & Nankivell tries; Hunt conversion & two penalties) Auckland 9 (Plummer three tries)