Sizing John gave Jessica Harrington her first victory in the Timico Cheltenham Gold Cup with her first runner when coming home a clear-cut winner of jumping's blue riband prize.

Given a patient ride by Robbie Power, the seven-year-old completed the English-Irish Gold Cup double in style to dispel any stamina doubts. Djakadam travelled well for most of the race and looked as though he might end Willie Mullins' hoodoo in the showpiece event, but Sizing John (7-1) pounced to lead between the final two fences.

So often in the shadow of Douvan over two miles, Sizing John kept on strongly up the hill to score by two and three-quarter lengths from the staying-on Minella Rocco (18-1). Native River (7-2) was a short head away in third and Djakadam - twice the runner-up - was fourth.

Owner Alan Potts said: "It's unreal, it's my dream and it's come true.

"It's our first runner in the race, the jockey's first ride and Jessie's first runner."

Harrington said: "I can't believe it, it was amazing how he jumped and travelled.

"Robert said he wasn't going to go down the inside, but he did.

"It's absolutely fantastic, my first runner in a Gold Cup.

"He was running over two miles, but it was Robert 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 got to get a Classic now (on the Flat)!"

Power, who won the Grand National on the Gordon Elliott-trained Silver Birch in 2007, said: "Unbelievable, Jessica Harrington is a genius.

"I always said when this horse stepped up in trip he'd win.

"It's 10 years ago I won the National, I'm 35 now and appreciate it a bit more.

"Everyone has done a top-class job, it means more than any winner I've ridden for Jessica."

Power went on: "I had a lot of confidence in this horse, ever since the first day I rode him behind Douvan.

"We upped him to two and a half and then up to three - I was fully confident he'd always stay.

"I ended up jumping to the front at the second-last and I didn't want to do that until the last, but I was confident he'd stay up the hill.

"The plan was to be in the middle of the fence and keep out of trouble, but it was crowded on the outside so I took a chance and went down the inner and it worked perfectly. When you're on the best horse you can go anywhere.

"When he won at Thurles he didn't win until stamina kicked in and that convinced me he'd stay. It's thanks to Alan and Ann for letting us up him in trip and we said we'd come here after winning the Irish Gold Cup." Cue Card fell at the third-last for the second successive year, while Lizzie Kelly only got as far as the second fence where she and Tea For Two parted company.