Auckland's four-year, 19-match unbeaten run on Eden Park is over. Not since July 20, 2011, when they went down 32-25 to Otago in a midweek clash, had they lost at home before today.
But they made too many first-half errors in this tight clash in front of a crowd of 5480.
Canterbury were far from perfect but go 3-0 with 14 competition points and can thank wing Johnny McNicholl for two brilliant solo tries.
Auckland hammered away in the dying throes, with good impact from the likes of debutant Airi Hunt, but yet another conceded intercept try and a contentious first-half call were costly.
The good news was prop Charlie Faumuina emerging relatively unscathed from his 40 minutes, despite falling off a tackle on McNicholl.
"I got a bit of a hit on the shoulder but good to come out of that [game] with no other injury. I just wanted to get some good set-piece for our backs," said Faumuina, one of just two Aucklanders who had played the last time they lost on Eden Park.
His routine tomorrow morning will be the same as he awaits the call from the All Blacks selectors.
"Same as every Sunday, just have brekky with the family. If I get the good call, great, otherwise I'll be back playing for Auckland. It's just good to get out there after a frustrating three or four months," said the 28-year-old.
Auckland coach Paul Feeney liked what Faumuina did in his half of rugby.
"Anyone who hasn't played for three months will be blowing. I thought he put in a bloody good effort. He loves wearing the Auckland colours, he scrummaged well - their loosehead was under pressure - and he got round the field, carried strongly and had a presence in cleaning [out] as well," said Feeney.
Now it's over to All Blacks trainer Nic Gill to get some hard conditioning into him.
Charles Piutau is another fringe All Black hoping for a call tomorrow and he, too, came through unscathed.
"You just have to carry on with life," he said. "If the phone call comes, it will come. There's nothing I can do about it."
The first half was more even than the 19-8 scoreline would suggest, with a try to Canterbury loosehead prop Daniel Lienert-Brown, who looked to be in front of kicker Patrick Osborne. TMO Shaun Elliott ruled he was legal.
Auckland's try went to No 8 Akira Ioane but they conceded their third intercept try in three games when Ryan Crotty swooped on Simon Hickey's pass.
Auckland fullback Lolagi Visinia botched two kickoffs before Hickey assumed the duties.
Auckland's best were industrious and effective wing Bryce Heem, and second-five George Moala was a handful. The latter scored his third try in as many games.
Feeney took off both his captains in the 65th minute, leaving replacement prop Sam Prattley with the captaincy armband.
After the match, a presentation was made to one of Auckland rugby's favourite sons, Keven Mealamu, whose provincial career ends on 65 games.
In the curtainraiser, the Auckland Storm crushed rivals Canterbury 70-8 for their second-straight win in the women's NPC.
Canterbury 27 (J. McNicholl 2, R. Crotty, D. Lienert-Brown tries; T. Taylor 2 con, pen)
Auckland 21 (A. Ioane, G. Moala tries; S. Hickey con, 2 pen, J. Hickey pen)