Invasor lived up to his billing as the best racehorse in the world when he won the £3m Dubai World Cup on Saturday.
The five-year-old American challenger - ridden by 19-year-old Fernando Jara - came home ahead of another American horse, Premium Tap.
Hong Kong runner Bullish Luck finished third but there was disappointment for Frankie Dettori aboard Discreet Cat.
The unbeaten four-year-old, the only horse to beat Invasor in 12 starts, never got going and finished last.
Invasor, winner of last year's Breeders Cup Classic, had to fight hard to get his head in front.
"I never doubted that Invasor could win"
Premium Tap came back but Jara had just enough left in the tank of the 5-4 favourite to get him home, having time to wag his finger in joy at the crowd as he passed the line.
"To win this race is very special," said Jara, known as the "Ice Man".
"It was a little tough in the end but I had a good horse that exploded. He's tough and I owe him a lot."
Trainer Kiaran McLaughlin spent 10 years in Dubai at the start of his career and was delighted for owner Sheikh Hamdan al-Maktoum, part of the ruling family.
"All the good champions get beaten at some point and he will be back"
"I never doubted that Invasor could win. He did look around a bit and Premium Tap gave him a real race but I never doubted him at all."
A devastated Frankie Dettori was at a loss to explain the poor performance of Discreet Cat.
"He was beaten by a long way," he said. "I don't know if he didn't stay the distance or what, I can't tell you why."
Racing manager Simon Crisford added: "We will give him some time out now and then get him back to America.
"It was very disappointing but all the good champions get beaten at some point and he will be back."
Epsom Derby winner Sir Percy could only manage fourth in the Dubai Sheema Classic, his first outing since a disappointing seventh in the Champion Stakes at Newmarket in October.
The Group One race was won by Vengeance of Rain, trained by Hong Kong-based David Ferraris.
The six-year-old, ridden by Anthony Delpech, came with a sustained run down the middle of the Nad Al Sheba track to outstay Oracle West.
Youmzain pipped Sir Percy in a photo finish for third place.
Asiatic Boy pulled away for an easy victory in the US$2m UAE Derby, with Kentucky Derby prospect Day Pass a disappointing ninth.
Asiatic Boy, bred in Argentina, finished nearly 10 lengths ahead of runner-up Jack Junior, with Adil third.
"This is the best horse in the world," said winning jockey Weichong Marwing.
In the first big race on the sport's richest card of US$21.25m, Spring At Last won the $1m Godolphin Mile by two-and-three-quarter lengths ahead of Parole Board. Mullins Bay was third.