Menorah put in a superb display to beat the favourite Silviniaco Conti and win the Charlie Hall Chase at Wetherby.
The 8-1 chance ridden by Richard Johnson and trained by Philip Hobbs was well in sight of the long-time leader for most of the race.
But the well-fancied Silviniaco Conti, trained by Paul Nicholls, faded with three fences to go.
Menorah moved up to the lead to finish ahead of Taquin Du Seuil (10-3) with Double Ross (11-1) third.
Silviniaco Conti, who was making his seasonal reappearance, had set the pace for most of the race but he was never able to shake off his rivals.
Once the field turned for home, it was clear Silviniaco Conti would struggle to win the race for a second time after triumphing in 2012.
Taquin Du Seuil and Double Ross loomed large but Menorah, who had run over the flat at Sandown in April, emerged strongest and although his jumping was not the most fluid, he raced clear of the field to continue his trainer's recent good run of form.
"He's a fantastic horse, he's a Cheltenham Festival winner and he's won plenty of other races," said Hobbs, who was at Ascot.
"I think it's the first time he's won over three miles. I suppose you have to think about King Georges and races like that.
"That wasn't the first thought this morning but we're going to have to go that sort of route, I'd have thought.
"I suppose we needed Silviniaco Conti to run below par for us to have a chance, which he has. Anyway, he's run fantastic."