The new order among Australasian thoroughbreds will be shaped at Randwick on Saturday.

And Dwayne Dunn is banking on putting All Too Hard into the supreme position left vacant by his half-sister, Black Caviar.

All Too Hard and the New Zealand colt It's A Dundeel go around in separate races at Randwick, the former in the All Aged Stakes, the latter in the Queen Elizabeth Stakes.

By the end of the day one of them will have earned the right to the No.1 spot.

And if it is to be All Too Hard, he will have to run the best Sydney race of his career.

"It's going to be game on," Dunn said.

"His fitness will have to be right there, it's not like he's going in first-up against second-rate Group One horses.

"He needs to stamp his authority on it - and I think he can."

All Too Hard has raced five times in Sydney for one win and four mysterious efforts that have led to him being regarded as purely a Melbourne horse.

But Dunn doesn't necessarily subscribe to that view.

"You can say his Sydney form isn't as good, but there are reasons why," he said.

"When he went up there as a two-year-old he'd already had a long prep.

"Mentally, it got him off his game. He was bombing the start and doing things wrong."

Dunn believes All Too Hard has enjoyed a preparation as trouble-free as the one that provided him with the Caulfield Guineas win that is rated the best of his six victories.

"He's going as good as we can get him going," Dunn said.

"They've worked him out a lot more now, they know what he likes and doesn't like."

One of the "likes" will be the expected strong pace of Saturday's race that seems to be assured thanks to horses like Rain Affair and More Joyous.

Dunn also defended All Too Hard's mediocre trial at Randwick last week which he won only narrowly, saying he had looked after the colt on the slow track.

"It didn't work out like a trial that you win by six and everyone says he's flying," he said.

"He's got too good a turn of foot on the dry to be much good in the wet."

The All Aged is expected to be All Too Hard's last run in Australia before he begins a European campaign.

But Dunn warned he will have to run first or second to be assured of making the trip.