More Of That outstayed Annie Power up the famous Cheltenham hill to claim the Ladbrokes World Hurdle with Big Buck's back in fifth and subsequently retired.
Tony McCoy appeared to have dealt a hammer blow to More Of That's chances a couple of weeks ago by choosing to ride At Fishers Cross, who eventually finished third, and the winner's participation was only confirmed at declaration time.
Punters were not deterred, however, and he was sent off the 15-2 third-favourite in the hands of Barry Geraghty, who for the second time this week benefited from McCoy making the wrong choice.
Plenty still held chances at the bottom of the hill, but it was left to the two unbeaten young guns to fight it out, with More Of That, having just the fifth run of his life, powering to glory.
Trainer Paul Nicholls immediately announced the retirement of 11-year-old Big Buck's, the four-time winner of the race who only returned from injury in January.
Nicholls said: "He's going to have an honourable retirement, it's a sad day but it's good to end in one piece."
Geraghty said of More Of That: "It's great. AP was the first to congratulate me, there's no hard feelings - he's a true professional.
"He's a good horse. I was always happy. Ruby (Walsh, on Annie Power) was upsides me in the straight and he looked to be travelling and when he gave her a squeeze, the response was OK but I thought I had enough in reserve.
"It's only his fifth run. He jumped and travelled away. He was a bit innocent when he got to the front, a bit unsure but he kept going."
Trainer Jonjo O'Neill added: "He's still a big frame of a horse really and coming to himself. It all came together nicely, it's brilliant.
"He doesn't show you much at home, he's just a real class horse and goes about his business, never does anything flash."
Big Buck's was taken straight to the stables following the race, but after his retirement was confirmed, the ever-popular runner returned to the paddock to say farewell with one last walk around the ring.
Nicholls said: "Andy (Stewart, owner) and I have been talking about it and I couldn't improve him any more on what he's done today. We won't ask him to run again as he's been a wonderful horse and wonderful for racing."
Stewart said: "The great horse is not as great as he was when a nine-year-old.
"He had 420 days off (before returning in the Cleeve Hurdle) and he's obviously not sparkling any more. At Fishers Cross beat him in the Cleeve and has done so again and I think he is finding the years getting to him.
"We have done as much as we possibly can and there's no way we can improve on that - what you saw today is as good as he is but he owes us nothing.
"He's going back to Ditcheat where all my other retired horses are, and he'll be with Cenkos.
"It's been very flattering the way the public have taken to him.
"He's probably one of the greatest, if not the greatest, staying hurdler of all-time, and it's time to enjoy his retirement.
"He's been great for the public, great for racing and I love him to death."
Walsh said of Annie Power: "She was keen early and I didn't get her 100 per cent switched off.
"I probably got in a battle too early and picked the wrong JP McManus horse to follow.
"The winner found plenty, she stayed all right but he stayed better. I wouldn't mind riding the race again and challenging after the last rather than at the furlong pole.
"She jumped like a buck and she'll benefit greatly from a race like that, she's still a very good mare."
Rebecca Curtis said of At Fishers Cross: "He ran a brilliant race. I thought he was going to win coming down to the last couple of flights.
"I'm delighted that JP has won anyway."
Willie Mullins said of Annie Power: "I imagine she ran up to her mark, we were just beaten by a better horse on the day.
"She jumped well, I couldn't point to one hurdle and say she made a mistake.
"We'll see if she'll run again, there's Aintree or Punchestown which I would say might be favourite, but that was an extremely hard race and she might need a rest."
Meanwhile, David Pipe was thrilled to right last year's wrong as Dynaste returned to his potent best with a slick display in the Ryanair Chase.
The dashing grey was considered one of the bankers of last year's Festival when going down in a Jewson Novices' Chase thriller to Irish contender Benefficient, who was once again in a quality field for this middle-distance championship.
Dynaste ran with great credit when chasing home Cue Card in the Betfair Chase at Haydock in November, but had something to prove back at Prestbury Park having blown out badly when well fancied for the King George VI Chase at Kempton on Boxing Day.
His supporters stuck with him, however, ensuring he was sent off the 3-1 favourite, and it was clear Tom Scudamore was keen to give his charge a little more time to find his feet than has been the case in the past.
The eight-year-old could be spotted making good progress coming down the hill, but Scudamore continued to bide his time and produced him with a perfectly-timed challenge to join the front-running Hidden Cyclone at the final fence.
To his credit, Shark Hanlon's pride and joy tried to make a race of it, but Dynaste had too many gears on the run to the line and was good value for a two-and-a-quarter-length verdict.
His old adversary Benefficient travelled well for a long way, but dropped out quickly in the straight and was pulled up sharply before the final fence.
Scudamore said: "He's taken some knocks so I'm pleased for the horse as he's gone and shown how good he is, and he's gone and shown it at Cheltenham in a Grade One.
"What a thrill."
Earlier in the day, McCoy partnered Taquin Du Seuil to victory in the JLT Novices' Chase.
The O'Neill-trained 7-1 shot was noted moving into contention at the top of the hill and he swooped after the last to deny game front-runner Uxizandre.