Brett Prebble returns to the scene of his Melbourne Cup win on Green Moon with the assurance the stayer is in better form than when he won Australia's biggest race.

Prebble reunites with Green Moon in the Group One Australian Cup (2000m) at Flemington on Saturday, intent on adding the weight-for-age feature to his list of achievements.

And after seeing Green Moon at the property of owner Lloyd Williams on Thursday morning, the high-profile hoop is confident his trip from Hong Kong will be worth it.

"Go back through his form over the past 12 months and you'd have to say that (he's the one to beat)," Prebble said.

"He's proven himself and shown his ability already.

"And the mail is that he's going better than before he won the Melbourne Cup. So hopefully that's right."

Prebble returned from Hong Kong to ride Green Moon in his first-up run in the Futurity Stakes (1400m) where he finished fourth to All Too Hard.

He took plenty of positives out of the race over an unsuitable distance and said he saw a fitter racehorse on Thursday.

"He was bouncing on the track this morning," Prebble said.

He heads betting at $4 ahead of three-year-old Super Cool who has firmed to $4.60.

Green Moon has a great record at Flemington having won his past three starts there in last year's Group Two Blamey Stakes (1600m), the Group One Turnbull Stakes (2000m) and the Melbourne Cup (3200m).

He is out to join Makybe Diva and Let's Elope as the only horses to win the Melbourne Cup and Australian Cup in the same season since the Australian Cup has been run at weight-for-age.

"It takes a high-quality horse to win these 2000-metre weight-for-age races and that's what this horse is," Prebble said.

Green Moon is one of three Williams-owned horses in the race and Prebble feels stablemate Mourayan could pose the biggest threat.

"He's a pretty smart horse," he said.

Prebble has been a success in Hong Kong in his nine years there and is keen to stay for as long as his family is happy and he's competitive.

But he's also happy to return to Australia on big days if the opportunity is right.

He's already won a Golden Slipper and Melbourne Cup that way.

"People have given me some nice rides," he said.

"I'm not here and doing all the hard yards on them. Sometimes it just looks like you fly in and get the rewards and then fly out.

"But big race jockeys win big races, don't they."