Completing a spectacular treble on the card for Walsh and trainer Willie Mullins, the 10-1 winner was produced with a strong run towards the rail to land the spoils for owner Graham Wylie, already a three-time race victor with the great Inglis Drever.
It was only his second attempt at three miles, but the seven-year-old showed he had no problem getting the trip. He was held up in the early stages as 2015 winner Cole Harden set a strong pace that had the field well strung out. When he faded out of contention Lil Rockerfeller set sail for home, but Nichols Canyon was produced to lead on the run-in and score by three-quarters of a length.
Unowhatimeanharry, the 5-6 favourite, was three and a half lengths away in third without ever looking like continuing his winning run.
Wylie said: “When I told Willie to buy a horse for me, he rang me up and said ‘I think I’ve found you the next Inglis Drever’.
“He looks like Inglis Drever as he’s only a pony, but he flew up the hill. Ruby told me he’d ride him like that to make sure he got the trip. It wasn’t until approaching the last I thought he might get placed, never mind win.
“With the problems with Faugheen and Annie Power we thought he’d be a Champion Hurdle horse, but it hasn’t gone right.
“It’s only been the last two weeks he’s started to show anything, but this is great. Willie is a genius.”
Mullins said: “It was some performance. I didn’t particularly think the three miles would suit. But he learned to settle and Ruby got him settled out the back door and that made a difference. I imagine we were a little fortunate, too, as Ruby came over and got the rail and all the other horses were all at sea coming up the middle, but you take what you get.”
Walsh said: “He’s a little warrior. He switched off, he jumped and we just crept away. Lil Rockerfeller was battling back at me but he kept going all the way to the line.”
Neil King, trainer of Lil Rockerfeller, said: “He’s run a superb race and, to be honest, I thought he had it won.
“Trevor (Whelan) had him in the right place at the right time and the horse jumped beautifully. He’s as tough as they come and every run this season has been a career-best apart from the Cleeve Hurdle, when he came back sick.
“He travelled through the race so well today and we’re all very proud of him.”
Earlier Un De Sceaux produced his brilliant best under Walsh to prevail in a thrilling renewal of the Ryanair Chase.
The Mullins-trained nine-year-old won the Arkle Trophy at this meeting two years ago, but found a rejuvenated Sprinter Sacre a step too far in the Queen Mother Champion Chase 12 months ago.
Mullins avoided this year’s Champion Chase, where stablemate Douvan had been expected to dominate, and stepped up in trip. It proved a masterstroke.
Walsh eventually conceded to let the strong-willed gelding go to the front at the fifth fence and he gave a display of controlled aggression from there, producing a number of spectacular leaps.
Sub Lieutenant did his best to reel him in after the last, but the damage had been done and Un De Sceaux saw it out to score by a length and a half as the 7-4 favourite.