Western Warhorse caused a huge upset in the Racing Post Arkle Challenge Trophy at Cheltenham.
Champion Bumper and Supreme Novices' Hurdle winner Champagne Fever was an 11-4 joint-favourite to complete the Festival hat-trick and jumped superbly at the head of affairs under Ruby Walsh.
However, Western Warhorse tracked him into the straight under a confident Tom Scudamore and quickened up to lead after jumping the final fence.
Champagne Fever did his best to battle back, but 33-1 shot Western Warhorse passed the post a head to the good.
Champagne Fever's fellow joint-favourite Trifolium was four lengths away in third.
With Willie Mullins having already taken the opening Supreme Novices' Hurdle with the incredibly impressive Vautour, Champagne Fever was unsurprisingly popular with punters to complete a double for Ireland's champion trainer.
Everything appeared to be going well for most of the two-mile contest, with Champagne Fever fencing immaculately, but few would have expected the David Pipe-trained Western Warhorse to still be in with a shout on the run-in and he mastered the Irish raider under a jubilant Scudamore.
Irish Arkle hero Trifolium ran well in third without being able to match the front two after the final obstacle.
The major disappointment of the race was 2012 Champion Hurdle hero Rock On Ruby, runner-up behind Hurricane Fly in last year's Champion.
He made a shuddering error at the third fence and Noel Fehily did remarkably well to keep the partnership intact.
However, he was soon back-pedalling and never looked likely to land a telling blow.
Mullins said of Champagne Fever: "He's run a fantastic race.
"You'd be disappointed with the result, but not the performance. That's it for two miles. We'll step him right up in trip next season."
Charles Byrnes, responsible for the third home, Trifolium, said: "He's run a very honest race.
"He could never quite get to Champagne Fever at the second-last, but I'm thrilled with his attitude as he could have thrown the towel in but he didn't.
"I imagine he'll stay at the same trip next season."