Canterbury made it back-to-back Air New Zealand Cup titles with a thrilling 28-20 win against Wellington in Christchurch.

The red and blacks looked home and dry when Sean Maitland ghosted his way over to give Canterbury a 25-10 lead with 20 minutes to go.

But the sin-binning of Colin Slade in the 67th minute gave Wellington some hope and they fought their way back to 25-20 thanks to a converted try to Scott Fuglistaller.

That set up a tense final few minutes before Stephen Brett banged over a penalty to seal Canterbury's second successive cup final win over Wellington.

In fact it was Wellington's fourth straight defeat in Air New Zealand Cup finals and their seventh in eight national provincial final appearances since 1999 as they once again lived up to their title of provincial rugby's nearly men.

Slade starred for Canterbury until he was sin-binned for deliberately slowing the ball down.

His two first-half tries helped the red and blacks to a comfortable 18-3 half-time lead and he was in the thick of the action right from the start, going over in the second minute and dealing easily with the aerial bombardment from Wellington in the first half.

He scored his second try seven minutes before the break, finishing off a well-worked back-line move that gave him the space to beat Hosea Gear on the outside.

He did not fare so well in the second half though, an errant pass gifting Alipati Leuia an intercept try, then having to watch as Fuglistaller crossed the whitewash while he sat on the sidelines.

There were barely two minutes on the clock when Wellington wing David Smith lost the ball in the contact area and Sam Whitelock fed it inside to Slade who ran in unopposed.

Brett kicked the conversion then slotted two further penalties as Canterbury stretched out to a 13-0 lead with 28 minutes gone.

Having missed an earlier attempt, Piri Weepu got Wellington on the board with a penalty on the half-hour mark.

But any hopes of a swift comeback were quashed when Slade dived over for his second.

Wellington showed far more on attack in the second half as they looked to keep the ball in hand with replacement Fa'atonu Fili prominent.

But while they did finally get across the whitewash through Leuia and Fuglistaller, it was too little too late.