Frankie Dettori steered Golden Horn to a brilliant victory in the Investec Derby at Epsom.
John Gosden's three-year-old was sent off the 13-8 favourite for the premier Classic following a fine display in the Dante Stakes at York last month and Dettori settled the market leader towards the rear of the field for much of the mile-and-a-half Classic.
Dettori allowed his mount to ease closer from the home turn and he dispelled any doubts about his stamina as he quickened clear of stable companion Jack Hobbs (4-1) to give the popular Italian rider his second taste of Derby glory.
Just as he had done in the Dante, Jack Hobbs came off second best, beaten three and a half lengths.
Storm The Stars (16-1) was a further four and a half lengths away in third.
Golden Horn was not entered in the Derby but his impressive York victory led to owner-breeder Anthony Oppenheimer supplementing him for the race, despite his own doubts about whether his charge would get home over the 12-furlong distance.
Dettori was on board Jack Hobbs on the Knavesmire, with William Buick riding Golden Horn, but the two jockeys swapped places at Epsom after Buick's retaining owners Godolphin snapped up a majority share in Jack Hobbs.
Golden Horn's stamina was certainly tested, with Hans Holbein and Dante third Elm Park setting a furious early gallop before weakening out of contention.
Jack Hobbs, the 4-1 second-favourite despite concerns about the drying ground, was the first of the Gosden pair to show his hand, sweeping to the front inside the final furlong.
But he had no answer to Golden Horn's superior turn of foot and the market leader was well on top as he passed the post under a jubilant Dettori, who said: "Unbelievable - I still can't believe I've won the Derby again. What a feeling. Fantastic.
"I knew he was a good horse, it was up to me to mess it up, but everything went right."
Giovanni Canaletto did best of Aidan O'Brien's three runners in fourth, one place ahead of French raider Epicuris.
Irish raider Success Days, another who was supplemented, was last of the 12 runners.
"He hit a flat spot, but he flew at the end. When he found top gear, he was off." - Frankie Dettori on Golden Horn
Dettori's Derby triumph comes eight years after his first aboard Authorized in 2007.
He said: "We've won the Derby! I can't believe it.
"It was brilliant. The horse was magnificent. I was just a passenger.
"He hit a flat spot, but he flew at the end. When he found top gear, he was off.
"John has won it without me and I've won it without him and, finally, 20 years later, we're back together and we've done it together.
Gosden has waited even longer for his second success, with Benny The Dip his first Epsom hero in 1997.
Gosden said: "He (Golden Horn) was quite keen early and I thought Frankie dropped him out beautifully. The last thing I said to him was ride a cool race, and he rode a cool race.
"I thought it was a great ride and he's a proper horse.
"Jack (Hobbs) has run the most superb race. He was beautifully balanced by William down the hill into the straight. He ran a blinder and all being well he can go to Ireland (Irish Derby).
"It's great to be here."
Buick said of Jack Hobbs: "I'm very proud of him. It's all come very quick for him and he'll be a lovely horse in time.
"He ran a great race and they are two lovely horses, the first and second. On the day the winner was just better.
"I knew when I pressed the button Frankie would be on my tail.
"It was a smooth race to ride in, he came there with a good chance and he ran his heart out.
"You'd have to look forward to him for the rest of his career.
"I'm very happy for John Gosden, it's an unbelievable feat and I'm far from disappointed to be second."
William Haggas said of Storm The Stars: "I'm chuffed to bits with him. He ran great, he was well ridden and he stayed on well.
"He'll stay further and he's going to be a nice horse and we'll look after him.
"You'd have to look at that (St Leger), but we'll just see how he is.
"He keeps getting better and third in the Derby - I'd have settled for that this morning."