DEL MAR, Calif -USA (AP) — Mike Smith tried everything he could with Arrogate . He even moved the colt to the outside, but he didn’t pick up the pace. Smith dropped him down near the rail before wheeling him outside once more.

Nothing worked.

“He just wasn’t trying,” the Hall of Fame jockey said.

Accelerate stunned overwhelming favourite Arrogate to win the US$300,000 TVG San Diego Handicap by 8 1/2 lengths Saturday at Del Mar, snapping the seven-race winning streak of the world’s top-ranked horse.

Arrogate finished fourth, beaten by 15 1/4 lengths in the 4-year-old colt’s first race since March 25 in Dubai.

“I’m at a loss for words,” Smith said. “He was just flat, so flat.”

His trainer, Bob Baffert, was blunter, saying Arrogate “laid an egg”.

It wasn’t the first time Accelerate got the best of Arrogate. Last year at Los Alamitos, Accelerate beat Arrogate by a neck in the colt’s career debut, in a race won by another horse. It was Arrogate’s lone loss until Saturday.

“I thought he’d run better than that,” Baffert said, “but he just didn’t want to go”.

Accelerate lived up to his name, leading all the way while covering 1 1/16 miles in 1:42.15.

“He got in a nice rhythm; he was going easy,” said Espinoza, aboard for the first time. “I was surprised by how far I won. I wasn’t surprised that I did; I was here to win.”

All but US$214,466 of the US$2,671,938 total win, place, and show pool wagering was bet on Arrogate, the 1-20 favourite.

It wasn’t the first time Baffert had led a world-beater to the track, only to watch him lose.

That’s what happened in 2015, when American Pharoah was stunned by Keen Ice in the Travers, barely two months after becoming horse racing’s first Triple Crown winner in 37 years.

“That’s why my hair is white,” Baffert quipped after the race.

Under the race’s handicap conditions, Arrogate carried high weight of 126 pounds, spotting Accelerate nine pounds. But Baffert said the weight difference had nothing to do with the result.

Heading to the rail beforehand, Accelerate’s trainer, John Sadler, said he thought the race would be closer than people thought.

“You want to win, you don’t want to concede anything, but I’m surprised we won because Arrogate is the best horse in the world,” Sadler said. “A couple of things went right for us and one of them was that Arrogate didn’t fire his best. That’s what has to happen for these big upsets.”

With Accelerate setting the pace, Smith had Arrogate last through the opening half mile before they began making their move into the far turn. But Arrogate’s rally was brief while Accelerate cruised to the finish line in front of a shocked crowd.

Arrogate will have a chance to turn the tables in the US$1-million Pacific Classic on August 19, when the two colts are expected to meet again.

“We’ve got to go back and start over again,” Smith said. “Get it back right.”