First-up expectations are being kept in check for Invest but trainer Heath Conners believes another big-race win is within reach before the mare is retired.

Last year's Australasian Oaks winner kicks off what's expected to be her final racing campaign in Saturday's Listed John Dillon Stakes at Caulfield over a distance short of her best.

But the manner in which the four-year-old has returned to work gives Conners confidence to aim the mare at the Group One Australian Cup (2000m).

"Peter Mertens came out and rode her on Wednesday morning and said she's definitely bigger and stronger," Conners said.

"He said if anything it's the best she's ever felt."

While Conners is not expecting too much from Invest over 1400m, the Caulfield race will provide a launching pad into the Melbourne autumn carnival.

Invest is a $51 chance in the John Dillon Stakes where she'll carry 60kg.

"As long as she's hitting the line strongly I'll be happy," Conners said.

"She's nominated for the Australian Cup and we're heading in that direction.

"It's a big target but there's no reason why she won't go on after that as well. She can still go to Adelaide and Brisbane after that.

"She'll probably go to stud at the end of this season and I think she's the sort of mare that the more races she gets under her belt the better she'll go."

British General, who has won his past three starts including the Listed Chester Manifold Stakes, is the $2.70 favourite for the John Dillon Stakes.