The Willie Mullins-trained 7/4 shot overtook his rival just before the last as they moved past long-time leader So Young who made a mistake.
Zaidpour raced away for the win with Voler La Vedette only managing third in the end as Monksland finished strongly to place in the five horse race.
Zaidpour is now likely to go head-to-head against Big Buck's in the Labrokes World Hurdle at Cheltenham in Mark.
"I think he's improved so we'll go along those lines," said Mullins.
"I doubt he'll take on Hurricane Fly next (in the Champion Hurdle) but he'll be entered in all those races. He has enough speed for two miles, but he has plenty of stamina, too."
"It was a fantastic result and he's stronger this year. He's good enough to run in a Champion Hurdle but the obvious thing would be to go over a longer trip.
In other Grade One action at the course, Arvika Ligeonniere won the Bar One Racing Drinmore Chase in impressive style to give Mullins another big win.
Once again it was Walsh on board as he romped home to a victory as a 2-1 shot by 11 lengths from even money favourite Dedigout Evens.
Walsh had to settle for second place on board 11/8 favourite Champagne Fever in the Bar One Racing Royal Bond Novice Hurdle though as the Jessica Harrington-trained Jezki (9-4) won in the hands of Barry Geraghty.