Damien Oliver will ride boom filly Earthquake in a crucial barrier trial with a view to partnering her in the Blue Diamond Prelude if a knee injury keeps Kerrin McEvoy out of the race.

McEvoy fell from the Mike Moroney-trained Massale before the home turn in the Karaka Million in New Zealand on Sunday.

He escaped relatively unscathed but has ruled himself out of riding this week and is expected to have scans on his knee on Tuesday.

McEvoy is stable rider for Sheikh Mohammed's Darley operation in Australia.

The Peter Snowden-trained Earthquake is second favourite for the Group One Blue Diamond Stakes on February 22 and has her first public appearance in Victoria in Thursday's trial.

Darley's Melbourne foreman Paul Snowden said Oliver would ride the filly in the trial but, if fit, McEvoy would be aboard in the Fillies Prelude on Saturday week.

"He (Oliver) will trial her and he knows the deal so he's comfortable with that," Snowden said.

"The way he (McEvoy) is talking, he's probably a 60-40 chance of making the Prelude. We'll just have to wait and see what the scans say and what damage has been done.

"Obviously if Macca can't ride then he (Oliver) will ride her in the Prelude and then after that will be subject to what goes on with Macca, as far as the Diamond goes," he said.

Earthquake has been in Melbourne for just over a week and Snowden said she had settled in well.

"She's super," he said.

Earthquake has been deposed as the Blue Diamond favourite by Saturday's Randwick winner Rubick who will be sent south at the end of the week.

The Gerald Ryan-trained colt will run in the colts and geldings Prelude on the same day Earthquake competes at Caulfield.