Ballyburn went off odds-on favourite but it was Lecky Watson who prevailed in the Brown Advisory Novices' Chase at Cheltenham.
In an all-Irish affair, Ballyburn almost went down very early on and while Paul Townend was able to remain in the saddle, the four-time Grade One winner struggled with his jumping and was unable to make a mark on the race.
It prised the door for another Willie Mullins runner in 20/1 shot Lecky Watson to surge clear and cross the line with ease ahead of Stellar Story and Better Days Ahead.
An unexpected victory, jockey Sean O'Keeffe dedicated his triumph to the late Michael O'Sullivan.
"Over the moon, I can't believe it," O'Keeffe claimed. "I thought he had a nice chance. I thought if I got him jumping he'd do well.
"It's amazing here, you never know what can happen. Michael O'Sullivan used to share a house with us here in Cheltenham. He loved this horse. This is for him."
Reacting to Ballyburn's performance, who underwhelmed with a fifth-placed finish, Mullins said: "We elected to ride Ballyburn in a gallop and jump. Jumping let him down, but there we are. We live and we learn."
For all information such as guides, horses and odds, be sure to explore our dedicated hubs where you can also bet on Cheltenham on every race and bet on the Gold Cup. Maximise your potential winnings with our Cheltenham Super Boosts and other Cheltenham Betting Offers. For expert analysis and predictions on every race, visit our Cheltenham Festival Tips page.