Colin Tizzard's progressive stayer Thistlecrack was an impressive winner of the Grade One JLT Long Walk Hurdle at Ascot.
Reve De Sivola was bidding for a record fourth victory in the contest but ultimately had to play second fiddle to the second season hurdler who ran out an impressive winner under Tom Scudamore.
Scudamore had to appeal against a ban and gain permission from Dynaste's trainer David Pipe and owner John White in order to be free to take the ride and the seven-year-old made it well worth his while with a smooth performance.
Settled in midfield as Reve De Sivola cut out a steady pace, the pair were always travelling strongly.
The leader's hurdling was far from fluent but he had still seen off the challenge of Saphir Du Rheu a long way from home but as he turned into the straight with two hurdles to jump, Thistlecrack was stalking Richard Johnson and travelling ominously well.
Scudamore gave him his office at the second last and he quickly asserted to go an and run out an impressive winner eight length from Reve De Sivola.
Deputy Dan finished third, another 12 lengths away, but the well-touted Saphir Du Rheu was a big disappointment with trainer Paul Nicholls reporting that the race may have come too soon.
That view was backed up by rider Sam Twiston-Davies who said: "He had a very hard race in the Hennessy. He probably just got a little bit tired. He is a Grade One-winning horse on his day and he will get back to that."
Scudamore said of the 2/1 favourite: "He gave me a lot of pleasure. It's a very special day. That showed me how good I think he is.
"He jumped very well in the main - he's a Grade One winner again.
"David Pipe (Scudamore's boss) said to me you can ride Thistlecrack but I had to just clear it with John (White), his owner. I spoke to him (White) when both horses were going for the race and John was very helpful and gave me his blessing.
"I very rarely get off one for David Pipe as he has been very loyal and good to me and it was tough to desert Dynaste on this occasion.
"He (Thistlecrack) has done everything that I've asked of and it was a very impressive performance."
Tizzard said: "I had it on my mind all summer that if he's not up to World Hurdle class we'd scrap that and go over fences. We said we'd give him two runs over hurdles to see if he's good enough and we now know what the answer to that is.
"He'll run again one more time before Cheltenham, otherwise I'd be left twiddling my thumbs with him for three months."
The Dorset handler added: "If you look at him, he looks a magnificent specimen of a chaser, but he is picking up an awful lot of money doing what he is doing.
"He just hurdles really accurately but he has got the scope for everything you could possibly want from a horse. He is a big, strong horse that travels well and stays any trip.
"Tom said it felt great and it looked great - he does everything so easily.
"When I first had him he was like a 13-year-old with a runny nose. Now he he has grown up you could not fault him as a racehorse."
Williams said of the runner-up: "I felt he was as well as he could be coming into the race. We are vulnerable to the up-and-coming youngsters.
"He might go for the Cleeve Hurdle but I don't know if I would want to take on Thistlecrack again.
"He has not got a good record in the World Hurdle so I doubt we would go for that we might just do something different. I thought he ran his race, though."