Trainer Archie Alexander is hoping the decision to focus on the Australasian Oaks in Adelaide with Mirette will be rewarded at Morphettville, rating the filly his best chance yet to claim a first Group One win.

Mirette was beaten just over two lengths when sixth in the Group One Thousand Guineas (1600m) last spring and Ballarat-based Alexander has specifically aimed the three-year-old at Saturday's Australasian Oaks (2000m).

"We kind of looked at Sydney and then looked at Adelaide and thought she's not bred to be a stayer and she's not a proper stayer, as in a 2400 to 3000-metre horse," Alexander said.

"So we thought we would leave the Sydney autumn alone and concentrate on this race over 2000 metres.

"We couldn't be happier with her and we're just hoping for a bit of luck.

"I think there's a couple of really strong horses in the race but I think we would be up there with equally a good chance."

Mirette showed she was on target for the Oaks when she finished strongly between runners to win the Group Three Auraria Stakes (1800m) at Morphettville on April 13, with Declan Bates retaining the ride on Saturday.

Sopressa won the same lead-up race last year before winning the Oaks.

"Like a lot of horses there's a little bit of a question mark over 2000 metres but I think her preparation has been ideal," Alexander said.

"We've gradually gone up in distance and we have never jumped her up a huge step in one go. She is training really well."

Since setting up his stable at Ballarat in 2014, Alexander has had 11 starters in Group One races including Lord Fandango who ran fourth in the 2017 Caulfield Cup a week after winning the Group Two Herbert Power Stakes.

"I think she is our best chance we've had but I know how hard they are to win, and we've been in a few with good chances and come up a bit short," Alexander said.

"To be honest you don't really think about it. If it happens, it's great but I'm not really worrying about it that much.

"We have three runners on the day and if it happens it will be an amazing dream come true, but we're a long way off that yet."