The track condition will determine whether talented sprinter O'Malley has his first-up run in a stakes race at Caulfield.
O'Malley is set to line up in the Listed Bel Esprit Stakes (1100m) on Saturday, his first run since finishing out of the placings at Sandown last November.
Enver Jusufovic is reluctant to run him on a firm track with Caulfield rated a good three on Wednesday, and the Cranbourne trainer intends to look at the surface on race eve.
While temperatures is forecast to be in the mid 20s, there is the slight chance of showers on Thursday and Friday.
"If it's not rock hard I'll more than likely run," Jusufovic said.
"We're getting a bit of dew in the mornings, but I'll probably go up on Friday, have a look and make some inquiries."
O'Malley showed promise as a younger horse winning four of his first eight starts before being sidelined for 18 months with a knee fracture.
Two screws now help hold the knee together.
The gelding lost muscle definition during his enforced break which he was able to recapture last campaign.
O'Malley had four runs last campaign before another break, three of them at Moonee Valley where he defeated All Aged Stakes placegetter Jungle Edge before his unplaced Sandown performance.
The gelding has done the necessary work in readiness for his return, including a soft trial when third behind Miss Vista and Merriest, both Caulfield winners last week, at Cranbourne on April 3.
"He's come back exceptionally well," Jusufovic said.
"It was a pretty soft trial and he derived benefit from that and his work on Tuesday was pretty good.
"Whatever he does he's going to improve on but he's rarin' to go, so it all depends on the weather what I do."
Jusufovic is reluctant to look too far ahead with O'Malley because of his previous injury, although he says the gelding is totally sound.
"I've got to see how he progresses," he said.
"The Goodwood (at Morphettville) is an option and we could then take him up to Brisbane."
O'Malley has opened $11 in betting on the Bel Esprit Stakes with country-trained Rocket Tommy the $5 favourite.