A freak accident has claimed the life of last-start Sydney winner Deep Chill as he was being prepared for the Sires' Produce Stakes at Flemington.

The David Payne-trained colt was one of the fancied runners ahead of Saturday's Group Two race for two-year-olds.

Deep Chill was working on the pro-ride track at Flemington on Thursday when he fractured a shoulder, resulting in travelling foreman Mark Whiteman falling.

"It was a freak accident, can you believe it," Payne said.

"He never gave us a day's problem, so it shows you what can happen.

"One of my foremen was riding him. He's got a broken cheekbone and he's a bit battered and bruised so I'm heading down a bit earlier to come and do the work."

Payne is hoping for a better outcome in Saturday's Australian Cup with Ace High in the Group One race.

The winner of the 2017 Victoria Derby at Flemington, Ace High will be running third-up in Saturday's race.

It comes after the four-year-old disappointed in the Caulfield and Melbourne Cups last spring when well back in both.

Ace High has trailed home Australian Cup favourite Avilius in both runs this campaign, including a last-start third in the Peter Young Stakes at Caulfield, but Payne expects the bigger Flemington circuit to suit.

"He'll enjoy the step up to 2000 metres and the speed in the race," Payne said.

"In the Cups last year he wasn't ridden right, which wasn't the jockeys' fault, but he gets out of the barriers so good and he found himself in front twice and he ran himself into the ground.

"I'm still keen to try him at those trips, but he needs to be ridden right, ridden back.

"He's a much better horse when he's covered up.

"We've got to beat Avilius. He's obviously the one to beat, but who knows, it's racing."