Apprentice Blake Spriggs was lucky to escape injury when his mount Circle Of Power collapsed and died in the final race at Rosehill on Saturday.

Spriggs sensed something was wrong with the Rod Craig-trained gelding at the top of the straight and tried to ease him out of the race.

As the horse succumbed to a suspected heart attack and crashed through the running rail at the 300m, Spriggs jumped and his only wound was a fat lip.

"I think I bit it on the way down," Spriggs said.

"The plastic running rail really helped me there.

"I tried to pull him up but then I just bailed out."

Circle Of Power was a Craig stable favourite and the trainer said he had shown no signs of any underlying problems.

"He's the best I've had him in a long time and I couldn't have been more happy with him," he said.

"It's just such a shock."

A veterinary examination at the scene determined Circle Of Power had most likely suffered a cardio-vascular episode with an autopsy to be held.

Circle Of Power earned more than $400,000 in his 42-start career which netted five wins and 12 placings.

All other horses avoided the incident with the race won by the Chris Waller-trained Riva De Lago.