After a titanic home-straight battle, Adequacy and rider Stephan Karnicnik were able to edge out Delacroix and James Seivwright right on the line.
"We both didn't know who won," Karnicnik said.
"He led by 15 lengths at the start and won by a nose!"
"It would have been a terrible race to watch."
Adequacy established his big break on his runner-up after the jumper made a fast beginning.
Karnicnik said his experience with flag starts, which do not use starting barriers, meant he was able to get Adequacy away quickly.
"He probably won it at the start.
"I have ridden a lot abroad and never used starting stalls until I came to New Zealand."
After making his brilliant beginning, Adequacy began to race keenly.
"I had to settle him; if there is no pace on, you are just going to fight him."
Adequacy has shown excellent form since joining trainer Kelvin Tyler's stable ahead of the jumping season.
Karnicnik had seen a lot of the horse when he was stabled with New Plymouth trainer John Wheeler.
"He was an impossible to hold horse; we sacked him two years ago."
Karnicnik has spent much of the time since he was working with Adequacy on the sidelines.
Several hand operations kept him out of action for much of last season.
Yesterday's victory was the 40-year-old's first victory since April of last year.
Adequacy was left with just three other rivals following a bizarre accident in the back straight on the last lap.
After seemingly galloping along contentedly between jumps, Irish Dude slipped and fell, taking his stablemate, Paddy Owen, out of the race.
Delacroix's second placing turned around the fortunes of James Seivwright, who crashed out of the Otago Hurdles after falling from Adequacy's stablemate, The Energizer.
The Energizer's front offside hoof landed on part of the final hurdle, which was left in pieces when rival Jackfrost clipped the top of it.
The Energizer was about to launch his customary big finish when he and Seivwright went crashing to the track.
That left Jackfrost, Banbury Lad and Cashel to fight out an exciting final 200m of the 2750m feature.
Banbury Lad unwound strongly to take the Otago Hurdles by a long neck over Jackfrost.
Cashel was a half head away from the runner-up in third.
Banbury Lad was ridden cold by Stuart Higgins, who waited until the home straight to work the 8yr-old into the race.
Higgins said those tactics were to make Banbury Lad a more versatile and settled horse before his big race assignments later in the season.
Jackfrost showed he was fit and ready for his upcoming Victorian campaign with his strong second placing.
Co-trainer Brian Anderton said he was pleased with the horse's effort and that Jackfrost pulled up in excellent order after the race.
Anthony Van Dyck gave Irish trainer Aidan O'Brien a record-equalling seventh victory in the Derby at Epsom early yesterday.
Seamie Heffernan's mount raced in mid-division for much of the way and still had more horses ahead of him than behind inside the final quarter-mile.
Stablemate Sir Dragonet and Madhmoon, trained by Kevin Prendergast, were disputing the lead over the final furlong, but Anthony Dan Dyck darted up the inside of the pair and galloped on strongly.
Madhmoon boxed on for second to deny O'Brien a clean sweep, as another O'Brien runner, Japan, flew home for third.
