A gelding procedure has had the desired effect on the manners of former bad boy Kingdoms who lines-up in Saturday's Hill Stakes at Randwick.

Once a rogue on the track and off it, the John O'Shea-trained four-year-old has settled down since he was cut following his autumn campaign.

"It's made a difference to my staff. They don't have to wear a full face helmet every time they walk into the box," O'Shea said.

"He used to rear up a bit, try and bite you and carry on.

"He's a lot better to handle."

The operation has also made a difference to his attitude to racing.

Kingdoms finished third in both the Australian Derby and Frank Packer Plate despite racing ungenerously both times.

First-up last month he beat one rival home in an unsuitable 1500m race won by Prince Cheri and importantly, he was on his best behaviour.

"He was very tractable in both his trials. He was very tractable the other day," O'Shea said.

"I was happy with him the other day. I thought he would have won if he'd gotten a bit of luck."

That was a benchmark race and Kingdoms will rise steeply in both class and distance on Saturday.

The scratching of Hawkspur, who will instead line up for Chris Waller in the George Main Stakes, has made Kingdoms' task only slightly easier.

Waller will still have a strong representation in Beaten Up, Kelinni, Moriarty and Bayrir while Gai Waterhouse starts Group One winner Glencadam Gold in the field of 11.

Kingdoms will tackle the 2000m race second-up and he will be making his weight-for-age debut.

But O'Shea has no reservations on either front.

"I know he's coming from a handicap to weight-for-age but it's not a big deal," he said.

"He was running around at level weights as a three-year-old.

"He was stakes placed behind It's A Dundeel and doing a bunch of things wrong."

Kingdoms is being aimed at the Metropolitan (2400m) at Randwick on October 5 and is a $13 chance for the Group One.

O'Shea also confirmed Rosehill winner Diamond Oasis would back-up in Saturday's Listed Heritage Stakes (1100m).