Winona Costin might be about to relinquish her crown as Sydney's premier apprentice, but she is just glad to be back riding after a run of injuries.

Costin steered Rock On Zariz to win Saturday's Highway Handicap on her first ride back from her latest setback.

At the beginning of the month, Costin came off two-year-old Hayman at trackwork with the colt standing on her leg.

"I had a pretty deep cut which needed two surgeries," Costin said.

"It wasn't his fault. He is the quietest horse and I can't wait to get back on him.

"All up this season I've had about three months off so I want to put it all behind me.

"It's just great to be back."

Rory Hutchings, whose apprenticeship ended earlier this month, has a healthy lead over his nearest rival Koby Jennings for the junior title.

The Barbara Joseph and Paul Jones-trained Rock On Zariz ($11) came from back in the field to claim the Highway (1200m) by a length from Charge Of Light ($21) with the favourite Star Shaft ($4.80) another long neck third.

"He travelled well and it was a strong win in the end," Costin said.