Former Godolphin galloper Zethus is set to make his debut for the Stephen Brown stable at Moonee Valley.

Brown has chosen the Group 2 Australia Stakes (1200m) as the gelding's first start after the five-year-old had an 18-start career under the guidance of James Cummings, registering three wins and four minor placings.

Of those three wins, two were at Stakes level while the gelding's third win victory came at Moonee Valley.

Zethus was a $120,000 online purchase and Brown did his homework on the gelding before deciding to take the punt.

"We had a look at all his records and my main owner wanted a nice horse," Brown said.

"I rang (Godolphin foreman) Reg Fleming a couple of times, and he checked up on the horse. He said the horse has a couple of little problems but was not broken.

"We got him home, X-rayed him here, there and everywhere, his feet, joints, there were no problems, but he's got a little chip in a knee that the vet said would not worry him

"He said he wouldn't even take it out, so we decided to go on with him, look after him, and that's what we've done."

Brown said he had been hoping to have Zethus ready to run first-up in the Group 3 Standish Handicap (1200m) at Flemington on January 13, but had run out of time.

Instead Zethus had an 850m trial at Tatura on heavy ground on January 10 and rounded out his preparation for a first-up tilt with a gallop at Moonee Valley on Tuesday.

Mickaelle Michel, who partnered Brown's longshot Flemington winner Southern Fire at Flemington last Saturday, rode Zethus in the gallop and has the mount on Saturday.

"She's a nice rider, a strong rider and she's pretty confident," Brown said.