Michael Rodd on Efficient (L) saw off Damien Oliver on Purple Moon
Efficient, ridden by Michael Rodd, shrugged off poor form to win the 147th Melbourne Cup with a devastating sprint past the British-trained Purple Moon.
The winner came from behind to edge out Purple Moon and the Irish-trained Mahler, which finished third after leading into the final straight.
The £2.26m handicap at Flemington was watched by a crowd of over 100,000.
Efficient had not won a race since last year's Victoria Derby, despite being favourite for last year's Cup.
The four-year-old gelding was withdrawn on the morning of the event in 2006 after going lame and had not won a race since.
I know I've done it but it's going to take a while to sink in; I feel numb at the moment
Winning jockey Michael Rodd
His connections were so worried that his trainer Graeme Rogerson recently started putting him over the hurdles but Efficient found his best form at the right time.
"I had to chase down Damien Oliver, who was riding on Purple Moon which was one of the favourites," said Rodd.
"I knew he'd be tough to get past but I had such a soft run, a bit light on the weights too, and it's just unbelievable.
"I know I've done it but it's going to take a while to sink in; I feel numb at the moment."
Purple Moon was close to becoming gthe first British-trained horse to win the race, but Cumani admitted he was never confident of lifting the prize.
"I could see the grey horse coming down the outside. I was just hoping his run had peaked. I wished he had found form next week," said Cumani.
Cancellation threatened the Cup after an equine flu outbreak two months ago.
Melbourne Cup officials were given the go-ahead to proceed after the highly contagious disease was partially contained and they agreed to major concessions.
Coolmore's Tom Magnier was full of praise for Mahler's effort and is expecting the Aidan O'Brien-trained three-year-old to rank highly next term.
"Stephen gave him a great ride - the run was absolutely the way we wanted, we knew he had to take it up," said Magnier.
"Aidan is delighted with the run and thinks he's going to be a serious horse.
"Efficient is a good horse who won the Derby down here and Purple Moon has been the talking horse down here all week.
"The two of them gave great runs - we wouldn't be disappointed with Mahler."