John O'Shea does not rate himself as an accomplished rider but he has proven to have an eye for one.

As the man who coaxed premier jockey James McDonald and Englishman Tom Marquand to Sydney, O'Shea has an exceptional record in talent identification.

Also a significant influence on the early career of Tim Clark, O'Shea keeps a watchful eye on world racing and says a key factor he looks for in emerging riders is good technique.

"There is a basic technique to riding and James has it. The capacity to change the whip, his balance, his seat on the horse. Fundamentally he is very, very good," O'Shea said.

Champion jockey in Sydney last year and the first to ride more than 100 winners in a season since Darren Beadman in 2006-07, McDonald is setting the pace to defend his premiership title.

O'Shea coaxed him over from New Zealand as a relatively unknown 19-year-old and says along with innate talent, McDonald's desire to win separates him from his peers.

It was a similar story with Englishman Marquand, who arrived for his second Australian stint with little fanfare and took the Sydney autumn racing carnival by storm.

Closer to home, O'Shea and McDonald will team up on Saturday with the consistent Southern Lad in the At Sea Handicap (1100m).

The sprinter has continued to thrive since his first-up second in the Wagga Town Plate and O'Shea expects him to relish a return to Randwick.

Juvenile Agrophobic has been scratched due to a wide draw but promising three-year-old Opacity will take his place in the Calyx@Coolmore Australia Handicap (1500m).

The winner of three of his five starts, Opacity will strip fitter for his first-up fifth to Soldier Of Love and has shown O'Shea all the hallmarks of a stakes-class galloper.

"He's drawn to get a good run. He was just a bit new in condition the other day and he pulled out into the centre of the track and that wasn't an advantage," O'Shea said.