The sides were locked at 23-23 with 24 minutes remaining before a lost lineout just out from Wellington's 22m area proved disastrous for the visitors. Wellington ran the ball and wing Ben Lam, who was a dominating figure throughout the game, fed another key figure fullback Wes Goosen down the sideline.
A danger every time he touched the ball, Goosen was able to race down the sideline to score what proved the match-winner for Wellington.
But to confirm their win, as North Harbour moved the ball looking for a breakthrough, first five-eighths Jackson Garden-Bachop pulled off a key intercept six minutes from the end and scored to seal the outcome.
North Harbour's defence was given a work out under those circumstances and it wasn't surprising they missed 16 tackles to three by the home team.
It was one occasion when Wellington's speed of hand outdid the North Harbour rush defence that saw hooker Asafo Aumua open the try scoring in the 17th minute. Wellington worked off a midfield drive by No.8 Teariki Ben-Nicholas and in the follow-up play a superb back-flip pass by prop Joel Hintz propelled the ball to Lam.
Running like a centre he set up the chance for Aumua down the right flank and he made no mistake.
But a Wellington turnover created a chance and once first five-eighths Bryn Gatland had controlled the ball he provided fullback Shaun Stevenson with a gap which he took at pace and then provided wing Tevita Li with the perfect wing's scenario to run in the try.
Wellington maintained their attacking approach and when they won a scrum after a maul close to the North Harbour line on halftime, Ben-Nicholas fed halfback Kemara Hauiti-Parapara the ball and he was able to get over the line to give his side an 18-13 lead.
Then, within a minute of the restart, flanker Du Plessis Kirifi burst through in midfield and Garden-Bachop made ground to give wing Malo Tuitama the try.
But just when Wellington needed to take control, North Harbour gained momentum of their own, firstly through a Gatland penalty goal, then from two pieces of skill.
From a 56th minute lineout, Gatland chipped the ball behind the Wellington backs and Stevenson ran through to take the ball, and then sensing space on his right he put a kick towards the corner. That gave wing Matt Duffie a chance to chase the ball which conveniently stayed infield long enough for him to touch it down. Gatland's sideline conversion levelled the scores at 23-23.
Duane Monkley Medal points: Ben Lam 3, Wes Goosen 2, Gerard Cowley-Tuioti 1
Wellington 35 (Asafo Aumua, Kemara Hauiti-Parapara, Malo Tuitama, Wes Goosen, Jackson Garden-Bachop tries; Garden-Bachop 2 con, 2 pen) North Harbour 23 (Tevita Li, Matt Duffie tries; Bryn Gatland 2 con, 3 pen). HT: 18-13
FT | A late surge from @WgtnRugby secures a 35 - 23 bonus point win over @HarbourRugby #WELvHAR pic.twitter.com/AMHn3A5nGd— Mitre 10 Cup (@Mitre10Cup) September 9, 2018