Samcro edged out Melon after an epic duel for the Marsh Novices' Chase with Faugheen a gallant and close-up third.
The trio had the race between them at the last and Samcro led into the final 100 yards.
However the eventual runner-up rallied strongly and the pair flashed past the post together. It took the judge a couple of minutes to separate them with the verdict going to the 2018 Ballymore Novices' Hurdle winner, under Davy Russell, by a nose.
Melon was finishing runner-up at the Festival for the fourth time while Faugheen gave valiant chase up the hill and was only a further length adrift.
Of the domestic team, Itchy Feet unseated rider with a circuit still to run following a series of unconvincing leaps but Mister Fisher ran really well to finish fourth.
Winning trainer Gordon Elliott said: "Samcro is one of the favourites in the yard. Obviously he was in the doldrums for a while, so to get him back and win a Grade One in Cheltenham is something else. You can see how much it means to everyone in the yard. A lot of people have done a lot of work with this horse - they've spent day and night trying to get him right.
"He hasn't been scoping clean and it's been hard to get him to scope right. We've done a lot of different things, like building him a new stable, and he's pulled it off today. Everyone was knocking him, saying this and saying that. I probably even lost a bit of faith in him myself, but the horses are flying and I just can't believe it."
"I am a bit of a pessimist, but I thought Melon had got us on the line, to be honest. He missed the second-last and Davy said that knocked the stuffing out of him. He jumped brilliantly apart from that. It was a great race to watch, with Melon, Faugheen and Samcro - that's what this place is all about."
Willie Mullins said of Faugheen, who has taken to fences with such aplomb late in his stellar career: "His following this year has been fantastic at home and now back at Cheltenham, where he has had some of his best days.
"He had trained and passed all his tests at home, winning two Grade Ones and a beginners' chase, and he had trained beautifully the whole way up and we left the decision to bring him over until the last minute. There was no reason not to bring him and we were hoping he would run a fantastic race one way or another and we are very happy with him."
Proud owner Rich Ricci said: "It was lovely. He was magic and has never jumped as well as he did today. I think if he had pinged the third-last he might have won, but it was a great run by Samcro and great to see him back.
"It was a hard decision to run him here, we are in the shop window of racing and you consider all things, as he is 12, but I'm delighted we did as the reception here was magic and he ran a stormer. He has been working the house down at home and you could see today that was some performance. If he pings that fence he is right there.
"I don't know (what happens next), it is a good question. We've got the Punchestown back in Ireland and I think the Irish would like to see him once more time, so if he is fit and well and ready to rock we will probably call it a day then. I'm not sure we will come back for the Gold Cup next year at the age of 13, but we will see what the horse tells us."
Of Melon, Mullins said: "He ran a fantastic race and that's the third second in a Grade One he has had here. The cheekpieces have definitely helped his jumping, as he was gaining lengths with his jumping and on the whole it was very good. Hopefully he might race in the big one (Gold Cup) in the future, as he jumps and stays."
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