The first Group One race of the season will be a campaign-defining moment for Brandenburg, who will be tested against 10 Group One winners.

A full field of 16 will contest the Winx Stakes (1400m) at Randwick on Saturday, including some of the early favourites for the biggest races of the spring.

Trainer John Sargent is happy to flush out exactly where Brandenburg fits into the mix but admits there is no slow road to discovery given the strength and depth of Saturday's field.

"He will take his part in it and he's ready to go. It is front up now because there is no hiding," Sargent said.

"From three to four, they've got to develop. Big money has been turned down for him to go to Hong Kong because the owners want to race him, money isn't their objective.

"But hopefully this will vindicate keeping him."

A Hobartville Stakes winner first up as a three-year-old, Brandenburg has been Group One placed in the Randwick Guineas and against older horses in the Doncaster Mile.

Sargent says he has matured significantly into his four-year-old season and the trainer believes now is the time to extend him out to a middle distance.

The Epsom Handicap (1600m), Golden Eagle (1500m) and Cox Plate (2040m) are all on the table and how Brandenburg performs in the Winx Stakes will go a long way to determining his spring path.

"He's a horse I think will eventually get out to 2000 metres this season," Sargent said.

"This is a good kicking-off point and we'll assess where we go from here, whether we stay on the Golden Eagle path or go up to a mile straight away.

"He's got to step up against the older horses now but he is ready to go."

Brandenburg had his final gallop on the Kensington track on Wednesday, working stylishly over 1000m with race jockey Rachel King aboard.

He has drawn barrier 12, immediately outside Caulfield Cup and Metropolitan Handicap favourite Master Of Wine.

Fourteen horses in the Winx Stakes field of 16 plus two emergencies are resuming, headed by multiple Group One winner Verry Elleegant.

Her Chris Waller-trained stablemate Funstar has been paid up for the Winx Stakes and the Show County Quality (1200m) in which she would face a rematch with arch rival Probabeel.