A try after the hooter had sounded from reserve prop Harry Allan saw the hosts barely survive a fierce challenge from North Harbour, clinging to a 31-25 victory.
Harbour, who had claimed the Shield just once, against Canterbury in 2006, were looking good to repeat the dose 13 years later, with tries to Mark Telea and Lewis Gjaltema seeing them come back from a 17-5 deficit at halftime, and 24-13 with 15 minutes remaining, to take a 25-24 lead into the dying stages.
A missed penalty from Brett Cameron with five minutes to go – from a simple position – saw one Canterbury chance go begging, but they were given another opportunity in the final throes.
A penalty from 40 metres out, on a tough angle, was turned down, with Cameron instead kicking for the corner. A powerful rolling maul put them close to the line, before earning a pivotal penalty advantage. Strangely, they opted against taking a drop goal, but their decision paid off as repeated drives towards the Harbour line eventually reaped rewards as Allan crashed over.
It was a brutal blow for Harbour on two accounts. Not only were they denied just their second Shield tenure, but the loss also sees them miss out on the playoffs in the Premiership, by one point to fourth-placed Auckland.
Auckland will now play the unbeaten Tasman in their semifinal next week, while Canterbury will turn their attention to a tasty clash against Wellington.