It was a heavyweight bout in the making but the weather didn't play ball and the sides were forced to play wet-weather rugby as persistent rain dogged the contest.
Canterbury didn't even venture in to Wellington's half during the opening 10 minutes, such was their placid start, as the home side shot to an early 8-0 lead.
But as Canterbury have a tendency to do, they found a way back in to the contest as Tyler Bleyendaal's right boot and a try to Joe Moody right on the hooter saw the visitors take a 16-15 lead with them to the halftime break.
Wellington openside Ardie Savea was then harshly sent to the sin bin by referee Nick Briant as the Lions were forced to box on with 14 men for the first part of the second half.
Playing with a man down galvanised the side though and halfback Tomasi Palu - Wellington's third-choice No 9 - scored a crucial try, which put Chris Boyd's outfit back in front.
Wellington five-eighth Lima Sopoaga, who is locked in a duel with Otago's Hayden Parker to be the competition's top points-scorer, added to the Lions' advantage with a penalty as they took a small lead to the final quarter.
Savea nearly made up for his earlier indiscretion in the 68th minute with an exciting break from a lineout but he could only link with replacement hooker Reg Goodes who didn't have enough pace to find the line as he was bundled out in the corner.
Injuries then forced the 19-year-old Savea from the side of the scrum to the right wing as he showed his versatility.
As the game rumbled in to the final seven minutes, Wellington were again shorn of personnel as replacement flanker Adam Hill was shown a straight red card for stamping.
Canterbury were sure they had found a late try to snatch the game but TMO David Walsh didn't see any evidence as Wellington grimly held on in the dying stages to record a crucial win.
Wellington 25 (Joe Hill, Ardie Savea, Tomasi Palu tries; Lima Sopoaga 2 pen, 2 con) Canterbury 19 (Joe Moody try; Tyler Bleyendaal 4 pen, con) Halftime: 15-16
