After enduring a bumpy start to her preparation, Idle Flyer is back on target for her Group One goal, and this week's Emancipation Stakes at Rosehill will be an important stepping stone towards it.

The mare's return to the races was delayed by a stubborn virus, forcing trainer Matthew Smith to kick her off over an unsuitable 1200m in the Wenona Girl Quality on March 7, Idle Flyer showing her class to finish an encouraging fourth.

She has since won a barrier trial to keep her ticking over, and will be back at the races on Saturday for the Group 2 Emancipation Stakes (1500m) for which she is an early favourite.

"We started in a race we didn't really want to start in because we had a few interruptions to her 'prep'," Smith said.

"She has been a little bit behind. Her run was good first-up, so she goes into this race fit and well, but is she at her peak yet? Probably not.

"She is ready to go, but one more and she will be cherry ripe."

In a busy afternoon for the stable, Smith will also saddle up Portland in the Neville Sellwood Stakes (2000m) and ATC Australian Derby aspirants Eureka Rebel and Dezignation in the Tulloch Stakes (2000m).

The three-year-olds are among the outsiders of the field, but both are proven at the journey and Smith says the pair will be better again over the 2400m of the Derby.

"Both look like they will stay really well," he said.

"I just want to see them hitting the line. The danger in these races is you get no tempo, and then they're not going to be suited.

"I don't know what the Derby field will be like. I thought it might lack a bit of depth in the staying ranks, and we'd give it a shot."

Eureka Rebel is by former Smith-trained triple Group 1 winner Fierce Impact, who made his name primarily as a sprinter-miler.

Smith also has Mountain Queen by the same stallion and like the Derby-bound Eureka Rebel, that filly is also showing stamina and has been entered for the Australian Oaks (2400m).

"The ones by him that we've got showing ability are more middle-distance horses. It would be nice if we could get one through to each of the (classic) races," Smith said.

Portland arrives at the Neville Sellwood third-up and while he faces stiff competition in the form of highly-touted European import Barnavara, Smith expects the gelding to improve out to a middle-distance and on a rain-affected track.

"He has been looking to get out to this trip," Smith said.

"He's not right at his top yet, but he's on the way and this will be another step in the right direction. His work has been good, and I can't fault him really."