The Sky Boy story is still only half-written with his Villiers Stakes win a stepping stone to much bigger targets including the Melbourne Cup.

Trained by Anthony and Edward Cummings, Sky Boy lived up to his $3.20 favouritism to win his fifth successive race in Sydney's summer showpiece, the Group Two Villiers (1600m) at Randwick.

He has made his way from benchmark 70 grade over the spring and summer to earn an automatic start in the Group One Doncaster Mile in April.

He sports the colours of Dato Tan Chin Nam who died in October with his legacy living on through his Think Big Stud syndicate managed by Duncan Ramage.

Among Dato Tan's big wins were four Melbourne Cups and Ramage said home-bred Sky Boy would be set for the 2019 race.

"He is bred to be a Melbourne Cup winner so that's what we will set him for in the spring," Ramage said.

"But first he will have a short break and have two runs into the Doncaster."

Sky Boy's obvious talent convinced Christian Reith to get down to 53kg for the Villiers with the four-year-old holding off Group One winner Aloisia ($17) by a half neck with My Nordic Hero ($9) another length third.

"He makes my job easy," Reith said.

"He jumps well and puts himself in a good position. I let him go at the 300 metres and he does the rest.

"It has been a fantastic job from the stable because it's not easy to get a horse up in trip then back in trip, up in grade. It's been a hard three weeks getting the weight off but all worth it."

Edward Cummings is soon to branch out on his own with Sky Boy to remain with his father Anthony at Leilani Lodge at Randwick.

Anthony Cummings has no doubt Sky Boy is a future Group One star.

"He used his speed to get a spot, relaxed and used his speed at the finish so in terms of race craft he has ticked every box now and had to because there was a Group One filly running on behind him," he said.

"He had to be that standard to win that race today.

"His Group One race will come and his turn will come. It's fantastic to see the plan come together.

"He had it in his mind that he was too big of a hurry. We had to bring him back two steps, get him to relax and use himself constrictively. It is all part of it.

"We're only halfway there."

Sky Boy is by Pendragon out of Zazabelle, both trained for Dato Tan by the late Bart Cummings with the latter third in the 1999 Melbourne Cup.

The gelding was trained by Anthony's other son James Cummings before he took up the position as head trainer at Godolphin.

"Every Cummings has has had a hand in this horse," Ramage said.