DELTA Work won the Glenfarclas Chase from stablemate Tiger Roll, as the latter just failed to end his career in a blaze of glory.
Dual Grand National hero Tiger Roll took to the lead as the race reached its latter stages - but Delta Work narrowly outstayed him to prevail on the line.
Owner Michael O'Leary said of the Gordon Elliott-trained Tiger Roll: "This is his send-off - he owes us nothing. He's been wonderful to come back here for the six, seven, eight years.
"He's been the horse of a lifetime and in many ways Cheltenham has been his spiritual home. He's won five times here in Cheltenham. I know he's won two Grand Nationals, but he started here in Cheltenham.
"To start off winning the Triumph Hurdle here as a four-year-old, then win the National Hunt Chase and three cross-country races, it's incredible.
"He's a legend."
An emotional O'Leary added: "I really would have loved to see Tiger go out on a win. It's hard not be disappointed. You've a winner at Cheltenham and I'm disappointed.
"It's just a magical fairytale on ground that doesn't suit him. He's gone out on his shield, he's a warrior and that's a Gold Cup horse that has beat him and only just on ground he wouldn't like.
"I'm actually upset - I would have loved to see him win it."
Jack Kennedy, riding Delta Work, said: "Unbelievable. He's been very disappointing all season and that's just brought out a new lease of life in him.
"He's done it very well, I'm delighted. He's always been one of my favourite horses ever, I'm delighted to get that with him."
Tiger Roll's rider Davy Russell said: "He went down on his sword, we always knew Delta Work was going to be his biggest danger.
"He's taken really well to it, I just couldn't shake off Jack, he was breathing down my neck the whole way.
"He went down on his sword, he's a great man. It's fantastic, he's always seemed to get me out of jail but unfortunately it wasn't to be."