David Eustace is of the opinion the Australian Guineas is an open race and could be won by a horse at double-figure odds.

Eustace thinks that his stable could be the one to supply the long-shot winner in the shape of Jet Propulsion, who is a $26 chance with TAB fixed odds for the Group One 1600 metres race at Flemington on Saturday.

"I think a lot of horses will show a lot of improvement second up and it's a more even race than what people think," Eustace said.

"It won't surprise me if there's a good odds winner in it.

"I'm not a betting man but I think Jet Propulsion is over priced."

Eustace was happy with Jet Propulsion's first-up fourth behind Poland in the Autumn Stakes at Caulfield where he ran home strongly.

"We've always had a good opinion of him but we didn't talk him up much in the spring as he was quite immature," he said.

Last campaign, Jet Propulsion's best effort was a third at his fourth start in the Group Two Stan Fox Stakes at Randwick.

"He still isn't fully furnished but he's getting there. He's a tough, gross sort of horse," he said.

"He should finish strongly but might be looking for 2000 metres. We're looking for a good run from him in a very open race."

The Ciaron Maher and Eustace stable also have $41 chance Grandslam in the race but they believe he's looking for more ground.

"I think his pedigree has kicked in and he's looking for 2000 metres and further," Eustace said.