The most-anticipated Sydney barrier trial appearance so far by a 2012-2013 newcomer ended in tragedy at Warwick Farm with the death of a blue blood filly trained by Gai Waterhouse.

Forget Me Not, the first foal of Amelia's Dream, a mare who had her own racetrack career cut short because of injury, broke down badly soon after the start of her heat on Friday.

One of the most expensive fillies sold at auction this year, Forget Me Not was euthanised after breaking a hind leg.

She was expected to trial well and launch a career that was certain to create much interest because of her impressive bloodlines.

Amelia's Dream, who was also trained by Waterhouse, won her only two juvenile starts by a combined margin of more than 15 lengths.

She was a pre-post favourite to win the Golden Slipper after a Silver Slipper Stakes win but her place at the top of markets was short-lived when she pulled up lame straight after the Rosehill lead-up race.

Amelia's Dream was eventually retired to stud after going amiss again during an unsuccessful comeback in 2009.

Forget Me Not cost her owners Dr Edmund Bateman and his wife Belinda $910,000 at the Australian Easter Yearling Sale.

"It's just disappointing and obviously devastating," the couple's bloodstock agent James Harron said.

The Batemans have compiled an extensive bloodstock portfolio headlined by Foxwedge, a Group One-winning sprinter who is standing his first season at stud in the Hunter Valley, since entering the ownership ranks five years ago.

Their tartan colours have become a fixture of major racing carnivals throughout Australia.