Bryce Heys is backing a jockey who has had better weeks to help his training career go to another level at Randwick on Saturday.

More by circumstance than design, Heys has engaged apprentice Winona Costin to ride Major Major as the stayer chases a hat-trick of metropolitan wins in the $100,000 McKell Cup.

Costin is in her first week as an apprentice indentured to Peter and Paul Snowden after splitting with champion trainer Gai Waterhouse.

In spite of the drama surrounding Costin's departure from Tulloch Lodge and an inability to use her 2kg claim, Heys expects the apprentice to give Major Major every chance.

Costin is a runaway leader in the metropolitan apprentices' title and while she might not have been Heys' first choice, the trainer is a fan.

"The boys who I would prefer to use are up in Brisbane but Winona does ride for me and I rate her as a rider," Heys said.

"I'm happy to reward her by putting her on."

Heys will be trying to win his first stakes race as a trainer since setting up Warwick Farm stables last year and Costin will be pivotal in ensuring she carries out a simple race plan from a wide gate.

"We'll just concentrate on just getting him out of the machine and not having the debacle like we did when he won at Randwick after he was slowly away and missed it by five (lengths)," Heys said.

"You just have to be focused to get him away cleanly. He doesn't have natural gate speed so I suggest we are going to be spotting them a margin.

"And it's going to be Winona's judgment on that when she wants to move."

Major Major is challenging Sense Of Occasion for favouritism after successive 2400m wins in benchmark grade at Randwick and Warwick Farm.

Costin will ride two-year-old first-starter O'Reilly's Angel for Heys in the Fresh For Kids Plate.

Lee and Anthony Freedman have also snapped up Costin's services for Charles In Charge in the Get Well Glenn Handicap.