Many of Winx's George Main Stakes rivals will come from her own stable but trainer Chris Waller can't envisage any of them beating her.

Winx is aiming for her third win in Saturday's 1600m-Group One race at Randwick and her 20th at the highest level.

Among the horses Waller will enter are Who Shot Thebarman, Comin' Through, Tom Melbourne, Unforgotten and Egg Tart with a couple to also be nominated for the Makybe Diva Stakes in Melbourne.

Waller said the declaration of weights for the Epsom and Metropolitan Handicaps would have a bearing on where some of those horses go.

"The weights of the Epsom will a big factor on where our horses go," Waller said.

"They come out on Monday and that will tell me a lot. They will help me decide what stays around and runs in the Epsom and what goes to Melbourne for the Makybe Diva."

"I feel it is quite an important race here.

"They can't beat her, but it is an important race for them."

While Waller will be busy juggling his spring team, the focus as always is on Winx.

"She is just constantly in the zone and everything has gone to plan," he said.

"The jump-out last week was perfect. It was just enough to get on top of her with the four weeks between runs.

"She will love stepping up to the mile.

"She galloped on Thursday and will have another one on Monday or Tuesday just depending on how quick the tracks recovers from the rain, then we will have the media morning on Thursday.

"That will be just to stretch her legs. It seems to work for her. We can't change it now."

Waller said Winx's next step towards an unprecedented fourth Cox Plate win was not set in stone.

"Her run beyond Saturday is not locked in yet," he said.

"It is likely to be in Melbourne but we haven't given up on keeping her here.

"She can go two weeks, four weeks, wherever she goes.

"I said at the end of last prep it is one run at a time and we will stick to that."