Champ returned in style to the smaller obstacles and won the Grade One Howden Long Walk Hurdle at Ascot.
Nicky Henderson's nine-year-old - last seen at the Cheltenham Gold Cup pulling up - retained all his ability to overcome Thyme Hill and Paisley Park in the extended three-mile showpiece.
The 4/1 chance was pulling double before the home turn with two flights left to jump and had to find extra in the closing stages as Thyme Hill put in a serious challenge.
But Jonjo O'Neill Jnr - recording a landmark first Grade One victory of his career - kept the JP McManus-owned gelding up to his work to prevail by a length and three-quarters.
Thyme Hill was runner-up for the second year running, although he reversed placings from 2020 with Paisley Park, who was three and a half lengths away in third on this occasion. Thomas Darby was fourth.
It was a bittersweet success for Henderson as he had to withdraw ante-post favourite Buzz on the eve of the race as the horse suffered a serious injury.
Henderson said: "We have got to decide which way we will go. He can go either way (fences or hurdles).
"He is still a Gold Cup horse, but he is still capable of winning a Stayers' Hurdle. So there is a big decision that we don't have to make today.
"It is great for JP, it's great for everyone - there is a lot to look forward to and we have to take these horses on and take them to where they belong.
"It is lovely to see him back and getting horses back when they have problems is our job and when that comes to fruition, from the team's point of view it is a terrific effort. Our team at home, to get him back - it was lovely to watch the horse enjoy himself like that. We can go either way with him now.
"He has to go left-handed over fences, (but) as you can see over hurdles he can go left or right."
Of opting to return in the Long Walk, he added: "There was nowhere to go, it seemed the obvious thing to do to give him a run over hurdles for his own good, for his own confidence."
A jubilant O'Neill said: "It's my first Grade One, I'll remember this!
"As a young boy it's what you want to do, ride a Grade One winner at Ascot. To do it for Nicky, JP and on a horse like Champ - it doesn't get much better. The adrenaline is through the roof.
"Nicky said not to disappoint him, I was in front too but he's won an RSA and has plenty of stamina. When Tom (O'Brien, on Thyme Hill) came to me he went again.
"He's a great horse. He only really had one run last year and Nicky has done a tremendous job with him.
"I've had three bad injuries this year and it's been slow to get going, but it only takes one horse to get you back. I'm very thankful to Nicky and JP for putting me on him."