In a stable rich in weight-for-age stars, Royal Descent stands out.

The only mare in Saturday's Epsom Handicap, she also adds a rare feminine touch to trainer Chris Waller's Group One record.

The champion trainer's dominance of Sydney racing has been built on the back of tough geldings and classy colts.

Of Waller's 35 Group Ones, Royal Descent and Red Tracer are the only fillies or mares to feature and both claimed those victories in gender-restricted races.

Waller says it shows how tough it is for mares to compete against the boys at the highest level, the task that faces Royal Descent in the Epsom Handicap.

There is also an historical reference through Sunline who was unplaced in the 1999 Epsom when she carried 1kg more than Royal Descent has on Saturday.

"They've got to be exceptional to win the Group Ones and there's only a handful of them for mares," Waller said.

"A champion horse in Sunline shows how hard it is (for a mare) to win an Epsom with a pretty big weight, which is what Royal Descent has.

"But I'm happy with where she's at. She's even better now than in the autumn. She was still a touch weak then which is why we only gave her three or four runs."

Royal Descent is one of four Waller runners in the Epsom Handicap and three of them dominate the top tiers of betting.

Boban is second pick behind Royal Descent to defend his Epsom crown while He's Your Man is regarded as the best of the light-weight chances.

Boban returns to Sydney after a bewildering effort in the Makybe Diva Stakes, although he has been sharpened up since with a barrier trial.

Waller said there were legitimate excuses in Melbourne, including Boban's dislike of racing inside horses.

It seems a poignant theory given the five-year-old's rails drawn but Waller disagrees.

"From barrier one, he can save ground and from the 600 metres he needs room," he said.

"I see barrier one as a huge plus. In my opinion it's like saving two kilograms."

He's Your Man fits the profile of recent Epsom winners - an emerging horse with a light weight, while Waller regards his other runner Lucky Chappy as one of the better outside chances.

If one of them can win it will give Waller the last four feature miles at Randwick with Boban's Epsom win last year sandwiched between Sacred Falls' successive Doncaster Mile triumphs.