Aidan O'Brien sealed his ninth Vertem Futurity Trophy as Magna Grecia won the final Group One of the British flat racing season at Doncaster.
The Charles Hill-trained Phoenix of Spain (11-2) finished second.
O'Brien's 50-1 outsider Western Australia was three-quarters of a length further back in third place.
Narrowly defeated by a neck in the Autumn Stakes by Andre Fabre's Persian King at Newmarket two weeks ago, Magna Grecia was two lengths off the pace coming into the final furlong of the mile race on good to soft ground.
However, the 20-year-old O'Brien, who also won this year's Irish Derby, found a gap through the centre of the field to record the two-year-old's second victory in his three races.
O'Brien senior said of his bay colt: "He's still a little bit green but he's coming forward. It was lovely, he will have learned a lot today, he's a lovely horse. We think a mile will be his thing."
A stewards' inquiry was called as there appeared to be contact between the first two horses, initially when Magna Grecia moved out to make his challenge and then just before the line, but there was no change to the result.