Green Moon thundered down the straight to win the Melbourne Cup, upsetting a host of highly fancied foreign horses to bring Australia's most coveted racing prize back home.
The Robert Hickmott-trained stallion charged to the front 300 metres from the line and held off fast-finishing Fiorente to win the punishing $7.8 million two-mile handicap by a length.
The Irish-bred six-year-old defied 22-1 odds and several quality European stayers to hand local jockey Brett Prebble his first Cup and owner Lloyd Williams his fourth.
Third-placed Jakkalberry finished a further length-and-a-quarter back.
Clad in blue and white silks, the Hong Kong-based Prebble punched the air in celebration as a packed crowd at Flemington Racecourse roared under leaden skies.
Prebble shook hands with Britain's Prince Charles in the crowd and said he knew the race won at the 1200 metre mark.
"It's a lifelong dream," Prebble said.
"I thought the only thing that could get him beaten was his stamina if he didn't stay the trip.
"But the feeling he was giving me at the 1,200 was the sort of feeling you only get from very good horses.
"I've been very fortunate to ride some champions and he's up there in the top 10."
Last year's winner Dunaden and fellow French stayer Americain, who won the 2010 race, were favourites in the lead-up but failed to mount a serious challenge.
The Mikel Delzangles-trained Dunaden started favourite despite carrying the top weight of 59kgs but finished 14th in the 24-entrant field, while Americain ran in 11th.
Americain's non-placing spared the blushes of Australian racing administrators, criticised for allowing local jockey and former Cup winner Damien Oliver to ride despite being under investigation for illegal betting.
Local media reported earlier that Oliver had admitted to stewards he had bet on a rival horse at a local race meeting two years ago.
Oliver, who won the 2002 race on Media Puzzle, had been scheduled to ride Green Moon at the Cup and the prestigious Cox Plate last month but the 40-year-old was dumped by Williams after the corruption allegations emerged.
Williams previously won the Melbourne Cup with Just a Dash (1981), What a Nuisance (1985) and Efficient (2007).
The property magnate imported Green Moon in 2010 after the stallion failed to make a major impression in Britain.
Green Moon's fortunes improved dramatically Down Under, although few had backed him for the Cup fter a disappointing seventh at last month's prestigious 2,040-metre Cox Plate.
"We put a lot of money in and a heck of a lot of effort so to get this result today is terrific," said Williams's son and racing manager Nick.
"God bless everyone who wrote him off."
Fiorente's second place brought further disappointment to trainer Gai Waterhouse, who had prepared two previous runners-up with Te Akau Nick in 1993 and Nothin Leica Dane in 1995.
Italian trainer Marco Botti's Jakkalberry was the best of the international entrants, with the Luca Cumani-trained Mount Athos finishing fifth.
Last year's runner-up Red Cadeaux, trained by Briton Ed Dunlop, came eighth, while the powerful Goldolphin stable's entrant Cavalryman was 12th.