Racetrack rivalry is set to spill over into the Rosehill jockeys' room with two of Sydney's leading hoops involved in the most-anticipated clashes on Silver Slipper day.

Hugh Bowman and Blake Shinn will turn arch rivals when they go head to head aboard exciting two-year-olds Astern and Defcon in the Silver Slipper.

A race later they will be at it again when Bowman links with Catkins in the Millie Fox Stakes, taking on Shinn aboard top mare First Seal.

Both contests are expected to be virtual match races and the two jockeys hold the aces.

While Catkins is popular with Sydney racegoers, First Seal is a special horse to Shinn.

"I've obviously got a soft spot for her because I won the Flight Stakes on her and a few other races and I'm looking forward to reuniting with her," Shinn said.

"Catkins has a great fresh record so it's going to be a good clash."

First Seal, who twice beat Winx as a three-year-old, hasn't raced for 10 months after a rare hoof condition ruled her out of the spring.

Shinn has ridden her in two recent trials and while he came away from those with mixed feelings, the mare's subsequent work has convinced him she is ready for the Catkins challenge.

"Her last trial didn't blow me away to be honest," Shinn said.

"But her work since has been pleasing and her first trial was really good. I'm expecting a great performance from her."

In a race of unusual sentiment for the jockeys, Bowman also professes to having a special bond with Catkins who he has partnered to six wins including last year's Millie Fox.

The mare's versatility could be crucial on Saturday in a race devoid of obvious speed.

"I wouldn't say she's as dominant going into the race as she has been previously with First Seal there but she's going well," Bowman said.

"She can lead, she can sit second, she can sit third. She's tactically very adaptable and that's why she's been so consistent throughout her career."

At $2.10, Catkins shades First Seal ($2.80) for favouritism.

Astern is an odds-on Silver Slipper favourite with Defcon ($3) regarded as his only serious threat.

Defcon sat towards the top of Blue Diamond Stakes markets until a blood issue prompted trainers Peter and Paul Snowden to abort Melbourne plans.

Both colts are among the top 10 fancies in Golden Slipper betting and Shinn expects his mount to make Saturday's race a showdown.

"Astern is a good horse so it's going to be a good clash between them as well," Shinn said.