Finian's Rainbow won a dramatic renewal of the Queen Mother Champion Chase.
Kauto Stone fell at the first and Wishfull Thinking crashed out early in the contest, falling into a group of spectators out in the middle of the track which meant they had to omit the final fence.
It almost caused carnage as Andrew Lynch had to steer long-time leader Sizing Europe around the final obstacle, with Barry Geraghty riding a slightly straighter line on the winner.
The pair battled gallantly up the hill, but it was Finian's Rainbow who pulled out more to win by one-and-a-quarter lengths.
Big Zeb was 15 lengths away from the first two home in third.
Richard Johnson, jockey on board Wishfull Thinking, was stretched into the racecourse ambulance as a precaution but was conscious and talking to officials.
Geraghty said: "It's a brilliant day - you dream of days like this. "I'm genuinely so delighted for Michael Buckley (owner), he has a good team of horses and he's been unfortunate with Spirit Son getting injured.
"He's had a good few disappointments this season, but he's had patience with this fellow and I really am delighted for him.
"I thought he had it to do to be honest, but he has turned the corner since Ascot. His work has been much better.
"We were hoping he was closing the gap but you couldn't say for certain that he was there. We know now he was."
Buckley said: "I'm speechless, to be truthful. I'm feeling remarkably emotional.
"It's true to say I wouldn't have any jumpers if it wasn't for Nicky. We've been together as owner and trainer and friends since the early 1980s.
"I can't imagine doing it with anyone else and this is just another notch in his long career.
"He (Henderson) has scooted past the all-time record (as winning-most trainer at the Festival) and I'm proud and pleased to be part of the day."
Henderson said: "It was a great race and it was a pity they didn't jump the last fence. It was a tremendous race between two very good two-mile chasers.
"I'm thrilled for Michael because he's put a lot into this game, he adores it and it's a special day."