Monterosso will not defend his title in the Dubai World Cup after the Godolphin horse was declared a late non-runner.
The six-year-old claimed the 10-furlong prize in the hands of Mickael Barzalona last year and the pair had been due to go for glory once again.
However, Monterosso is reported to be lame and will now miss the race.
The Dubai Racing Club tweeted: "There's a late scratching in the Dubai World Cup. Horse 9, Monterosso will not run. Horse 11, African Story to be ridden by M Barzalona.
"Monterosso is reported by Emirates Racing Authority as being lame in his left fore."