Group-winning sprinter Heatherly is favourite for the Carlyon Stakes at Moonee Valley but her trainers have warned a heavy track could force a change of plans.

Heatherly is at $3.20 for the Listed 1000m sprint and impressed in a jump-out at Flemington last week when she won by several lengths.

But a possible eight to 20mm of rain is predicted in Melbourne on Friday and co-trainer Simon Zahra said if the track was downgraded to heavy it would prompt a rethink with a long spring ahead.

"We don't like running horses first-up on heavy tracks," Zahra said.

"So hopefully we don't get a lot of that rain."

Heatherly ended her previous campaign with strong form in feature sprints, dominating the Group Two Rubiton Stakes (1100m) at Caulfield before her third in the Group One Oakleigh Plate in February when she led until the final 50m.

Zahra said they gave Heatherly a good spell after the Oakleigh Plate and he hoped that would be to her benefit this spring.

"She didn't have a lot of runs last campaign but it was over a fair period, so she got three months out which is a rarity going from autumn into a spring preparation," Zahra, who trains in partnership with Mathew Ellerton, said.

"We just gave her plenty of time to make sure she was over the campaign and she seems to have come back in great order."

The speedy mare's campaign is likely to include the Group One Moir Stakes (1000m) at the same track next month.

A short-course specialist, Heatherly ran along in her 800m jump-out last week and Zahra said the mare had shown her best when she was allowed to get into her natural rhythm.

He said there would also be improvement to come out of Saturday.

"She's not screwed right down. It's a long spring, but her trial the other day was a pretty good jump-out," he said.

"She did it quite strong and ran a bit of time. She had a good blow so she seems to have come back in good order."

Wild Rain, Beau Rada and Sunday Escape have been scratched from the Carlyon Stakes while Craig Newitt has picked up the ride on O'Malley replacing the suspended Michael Dee.