In a race meeting missing four of Sydney's leading jockeys, Gary Portelli is chuffed to have snared Brenton Avdulla for the mount on Sebring Sun in the Listed Rosebud.

Hugh Bowman, Blake Shinn and James McDonald fought out the finish of the 2014/15 Sydney jockeys' premiership but none will be riding at Randwick on Saturday.

Bowman is taking a short break, Shinn will join Kerrin McEvoy in England for the Shergar Cup jockeys' championship while McDonald is suspended.

Bowman partnered Sebring Sun to a first-up win at Canterbury last month and in his absence, Portelli reckons Avdulla is a more-than-able replacement.

"Hugh, Blake, Kerrin, McDonald, they're all out," Portelli said.

"I've got Brenton Avdulla so I was on the front foot pretty quick.

"He's ridden him before too. He was on him at his first start and I've had a good association with Brenton."

There are 11 nominations for the Listed Rosebud, including late entries Vanbrugh for Chris Waller and the Kevin Moses-trained Zoutenant.

Sebring Sun will tackle the race second-up after producing an electric finishing burst to break his maiden in midweek grade at Canterbury on July 29.

While it represents a class rise, Portelli sees Saturday's race as an opportunity for Sebring Sun to build on his confidence and says the Rosebud is also a genuine chance for the colt to claim a valuable stakes win.

"This will probably be the weakest race he takes on from here on in, as far as black-type races go," he said.

"I think he's definitely up to this level."

Nominations for the other feature race on Saturday, the Group Two Missile Stakes, have swollen considerably after the Australian Turf Club received just six original entries.

When nominations closed on Tuesday that number had more than doubled to 14.

The late entries include Group One winners Temple Of Boom and Royal Descent along with in-form duo Lord Leofric for David Pfieffer and the Tony McEvoy-trained Shiraz.

Portelli doesn't have a Missile Stakes runner but he has thrown in a belated entry for Cosmic Cameo to join stablemate Straturbo in a benchmark 85 sprint over 1000m.

He is hoping for a drying surface for Straturbo and says Cosmic Cameo will be monitored this week before a decision is made on whether he backs up from his fourth at Rosehill last Saturday.