Trainer Brendan McCarthy says missing a lead-up to the Blue Diamond Stakes may not be to Blondie's disadvantage.

The filly runs in Saturday's Group One race for two-year-olds at Caulfield having had only one start, for a win, at Moonee Valley on January 27.

Blondie was due to contest the fillies division of the Blue Diamond Prelude won by Catchy on February 11, but was a race morning scratching.

"She had a tiny bit of clear fluid coming out of one nostril and I got permission to get her scoped," McCarthy said.

"She had a bit of mucus down the airway so we decided not to run her.

"We got a blood done that day and her white cell count was elevated so it was the right decision not to run.

"Everything is all clear now and I'm happy with the way she's come along."

McCarthy says Blondie hasn't missed any work.

But he said if she had raced in the Prelude she may not be running for a share of the $1.5 million prize money on offer on Saturday.

"The biggest worry was whether we were going to get a run," McCarthy said.

"But the fact is she didn't have to run on a hard track that day and I don't know whether she would have lasted for another two runs.

"I think she's got another run left in her but having two, I don't know if it would have worked that way."

McCarthy has kept Blondie to her usual routine, preferring to work the filly on the Polytrack at Caulfield on Tuesday rather than take advantage of the course proper for her last gallop.

"She had a nice gallop," McCarthy said.

"I didn't want to change things around too much with her.

"I could have worked her on the course proper but they can get a bit lost out there being a young horse so I kept her to her usual routine."

Damien Oliver was aboard Blondie on debut but rides Tulip on Saturday and Chris Symons has picked up the mount.

Blondie is a $41 chance with Catchy the $5.50 favourite ahead of Pariah at $6, and Property and Tulip at $6.50.