The seven-year-old gelding, trained by Australian Robert Hickmott, emerged at the final turn to haul in Heartbreak City in the gruelling two-mile handicap.
It gave owner Lloyd Williams his fifth Melbourne Cup in the race's 156th running and jockey Kerrin McEvoy his second after his win on Brew in 2000.
"Jeez, he travelled well," McEvoy said from the saddle.
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"How lucky am I, mate? The elation is just unreal.
"Just a dream, mate, to win my second Cup. It's just a dream come true. I love these staying races, I love the Melbourne Cup."
Heartbreak City finished second and favourite Hartnell, one of five entrants from Godolphin, finished third, continuing the frustrations of the powerful stable owned by Sheikh Mohammed bin Rashid Al Maktoum.
Godolphin have entered horses into the Cup since 1998 for the return of only three runner-up finishes.
(Reporting by Ian Ransom, editing by Nick Mulvenney)
