California Chrome, ridden by Victor Espinoza, sprinted to victory in the $10-million Dubai World Cup on Saturday, beating Mubtaahij in the world's richest horse race.

Trained by American Art Sherman, the $1.90 joint favourite won the 2,000-metre race by 3.75 lengths, despite Espinoza having to battle with a slipping saddle during the ride.

"He likes to run clear of his horses, he doesn't like to be bumped around. Victor knows him, he did a super job," trainer Sherman told reporters after the race at the 60,000-capacity Meydan racecourse.

Hoppertunity came third of the 12 runners in the contest.

"We've come across a superstar on the dirt, as California Chrome is - fantastic, and I am honoured to run second to him," Mubtaahij's trainer Mike de Kock said.

A switch to a dirt track last year has helped to attract US horses to the event. Eight of the 12-horse field were American this year.

De Kock told reporters that he was still optimistic about runner-up Mubtaahij, owned by Sheikh Mohammed Bin Khalifa Al Maktoum.

"He certainly is not a horse that I want to give a break to now, he's a horse that I want to keep on with," he said.

Chrome, who was the favourite last year but came a surprise second, has been in Dubai for more than two months, whereas last year he arrived just 10 days before the race.

The five-year-old is owned by California Chrome LLC and is also the 2014 Kentucky Derby and Preakness champion.