HONG KONG  - The world's top racehorse Cirrus Des Aigles has withdrawn injured from Sunday's Hong Kong International Races in a major blow to the competition, one of the richest meetings on the global calendar.

The French gelding was set to headline a stellar line-up for the 2,000-metre Hong Kong Cup and was seeking to make it fourth time lucky at the meet, where he has failed to scoop a prize in his last three appearances.

But it seems that he was unable to shake off his Hong Kong curse after sustaining what Jockey Club vets described as a "soft tissue injury" in his left front tendon, according to the South China Morning Post.

He has now been scratched from Sunday's race card so that his injury can be treated.

"It is a relatively mild injury but it would be very unwise to run him in a race," said Dr Chris Riggs, the head of veterinary clinical services at the club, according to the newspaper.

However, executive director of racing Bill Nader remained optimistic that Sunday would still be a great race day. "Obviously, it's disappointing to lose the world's top-rated horse," he said in the SCMP.

"I think the depth of talent remaining right across our four international races gives us some top-quality compensation," he added.

Cirrus des Aigles became the top-ranked racehorse in training after British champ Frankel retired in October to go to stud.

His withdrawal leaves last year's surprise victor Hong Kong-based California Memory the front-runner for the title, having raced to a late win at the Jockey Club Cup in November on the same Sha Tin course as Sunday's meet.

This year for the first time one of Queen Elizabeth II's horses will also join the field - Carlton House came in second to So You Think at the Prince of Wales Stakes at Ascot in June and competes for the Cup in the British monarch's Jubilee year.

The Hong Kong Cup has a prize purse of US$2.8 million and is the world's richest turf race over 2,000m.

It is one of four Group One contests that will take place at Sunday's Longines Hong Kong International Races and offers the largest pot of money. Total prize money at the meeting is US$9.2 million.

The 2,400-metre Hong Kong Vase will see last year's winner Dunaden defending his title after failing to do so at the Melbourne Cup in November.

Britain's Sea Moon looks set to be the French horse's biggest challenger in the US$1.9 million race, having beaten him into second at the Hardwicke Stakes at Ascot.

Also featuring at the meet are the 1,200-metre Hong Kong Sprint and the 1,600-metre Hong Kong Mile, both usually dominated by the home team but with strong international challengers this year.

As well as providing top-flight racing, organisers hope to up the glamour stakes with Oscar-winning British actress Kate Winslet making an appearance in her role as ambassador for Longines, the Swiss watch brand, which is sponsoring the race for the first time.