Sydney: Australia’s horse racing community was on Sunday mourning the death of champion thoroughbred Black Caviar, who died on the eve of her 18th birthday.

The horse passed away on Saturday, the day before she would have turned 18, her ownership group said.

Black Caviar was unbeaten in all 25 races she ran before retiring in 2013 and is widely considered one of the greatest sprinters horse racing has seen.

“Today’s news is a shock to us all. Black Caviar was more than a champion racehorse, she was an important part of life for many people,” Neil Wilson, chairman of the Victoria Racing Club, said in a statement Saturday. “She was simply the best.”

One of Black Caviar’s most famous victories was in England at Royal Ascot, where she took the 2012 Diamond Jubilee Stakes in a dramatic finish.

“She was a remarkable horse who gave us all the ride of a life time and wonderful memories,” said her trainer Peter Moody.

Black Caviar had been suffering from illness, Moody told Racing.com. The horse was euthanised at the Scone Equine Clinic, near Newcastle, after giving birth.

“She had lost circulation in her fore legs. The only humane thing to do was to put her to sleep, unfortunately, which was very sad,” Moody added.

Jockey Luke Nolan, who rode Black Caviar to the majority of her wins, said he felt fortunate to have been “part of her wonderful career”.

“Most riders would give their right arm to get a chance to be a part of chapter of racing history like I was,” Nolan told Fox Sports.

“It’s a little bit of a hollow feeling, a blur, because she meant a lot to us.”