For the second year in a row trainer John Thompson has a filly ready to run the race of her life in the Group One Coolmore Stud Stakes at Flemington.

The trainer won the race with Nechita 12 months ago but says it's too hard to line up the form this time around as he prepares last-start Group winner Thump for the 1200m straight-track sprint for three-year-olds.

"She is going as well as what she can go, I'm pretty confident of that. It's just a matter of how she measures up against all the colts," Thompson said.

"There's about four different form lines coming into the race. There's horses coming back from the Caulfield Guineas, two Sydney colts coming through the Golden Rose, she is coming through fillies races and Missy Longstocking is the same. Then you've got a horse like Lion Of Belfort that's going through the grades nicely. So how do you know?"

Thump won the Silver Shadow Stakes first-up in Sydney before a close third to Bound For Earth and star filly Guelph in the Furious Stakes.

The filly held off Blue Diamond winner Miracles Of Life in the Group Three Champagne Stakes (1200m) five weeks ago at Moonee Valley.

Thump contested a four-horse jumpout up the Flemington straight last Friday, narrowly defeating Happy Galaxy and Sidestep with Zoustar fourth.

Zoustar is odds-on favourite for the Coolmore while Sidestep is also in Saturday's race.

"It was definitely a nice trial. We weren't out to break any land speed records, she did it nicely within herself and the couple of colts there were sort of pushed up a bit behind her so that gives you a little bit of confidence," Thompson said.

"And history has always shown whatever trials well up the straight runs well."

Zoustar, to be ridden by Jim Cassidy who is chasing his 100th Group One win, won the Golden Rose and toyed with his rivals in the Roman Consul Stakes at his most recent start.

Thompson is hoping he doesn't produce the same form in Melbourne.

"Look, if Zoustar runs up to his Sydney form, he'll win. End of story," Thompson said.

"He's just got to bring that down to Melbourne."

Zoustar worked on the course proper on Tuesday with trainer Chris Waller describing his second look at the straight track as "brilliant".

A stud deal for Zoustar is expected to be finalised before the Coolmore.