As he prepares to farewell the best stayer in his stable, David Payne is looking to one he hopes will make the grade with Costello to begin his campaign at Randwick.

Dual Group One winner Ace High has been in light work at Rosehill but has now found a new home at stud at Rich Hill in New Zealand.

He was in work in case he did not find a stud in time for this year's breeding season and Payne is thrilled the kiwis still see the value in producing stayers.

"I think he will get a go over there," Payne said.

"In Australia people don't want to breed stayers but in New Zealand they still do.

"The other big studs are supporting him at Rich Hill and I'm so pleased. I think he can be a success.

"He will leave here on the 15th for his new life and he leaves here a fit and healthy horse."

Ace High won the 2017 Spring Champion Stakes and Victoria Derby and finished second in the Australian Derby the following autumn.

He finished well down the track in last year's Caulfield and Melbourne Cups both run on soft tracks which were not to his liking.

Costello is by 2010 Melbourne Cup winner Americain, and although not as forward as Ace High as a young horse, Payne believes he will make it over longer distances.

The gelding runs in Saturday's Benchmark 78 race for three and four-year-olds over 1600m at his first start since he finished seventh in the Australian Derby in April won by Angel Of truth.

"He will go through the grades this preparation and then next time we will aim higher," Payne said.

"He is a young horse and he has plenty of time. Eventually I think he will measure up to the better races, probably in the autumn."

Payne also entered Seraph and Silent Explorer for Randwick but they are likely to go to Canterbury on Wednesday.