Sizing John stormed home in another pulsating Cheltenham Gold Cup to give trainer Jessica Harrington victory with her first entry in the prestigious race on the final day of the Festival.
The 7-1 shot charged up the hill under Robbie Power and stayed on strongly to win by two lengths after Djakadam made a mistake with two to jump.
Minella Rocco produced a late burst to finish second ahead of Native River, while Cue Card fell three flights from home for the second successive year.
Bred in England and trained in Ireland, the seven-year-old Sizing John also won the Irish Gold Cup in February and came up with an outstanding display of endurance to give both Harrington and jockey Power a first success in jump racing's blue-riband race.
Harrington, now the most successful female trainer in Cheltenham Festival history, said: "He was running over two miles, but it was Robert [Power] who said he would stay and he did. Thanks to everyone at home, it's all down to the team. I can't believe it.
"I've never had a runner in the race before so to train the winner – I don't know when I'll come down to earth. You can tell Robert did showjumping in his youth because I don't think he missed a beat the whole way."
Last year's runner-up Djakadam looked ominous until clattering into the second fence from home with Ruby Walsh in the saddle and could only finish fifth, ensuring trainer Willie Mullins has still never won the race.
Mullins savoured a four-timer with Walsh on Thursday, but missed out on the leading trainer award to Gordon Elliott despite saddling a double on day four.
It was Mullins who was leading the way after Paul Townend rode Arctic Fire and Penhill to victory in the County Hurdle and Novices' Hurdle respectively, with favourite Defi Du Seuil having won the Triumph Hurdle in hugely impressive fashion.
However, Elliott took the prize courtesy of Champagne Classic's success in the Martin Pipe Conditional Jockeys' Handicap Hurdle, which saw him join Mullins on six winners for the week, but ahead due to having more second and third-place finishes.
It was very much Harrington and Power's day, with Rock The World putting the icing on the cake for the duo by winning last race on a St Patrick's Day dominated by the Irish.