The transformation in Sierra Sue has been amazing as the Trent Busuttin and Natalie Young-trained mare attempts a second Group 1 win.

Sierra Sue took out the Sir Rupert Clarke Stakes (1400m) at Caulfield at her most recent outing on September 18 and will attempt to take out the Toorak Handicap (1600m) at Caulfield on Saturday.

If successful, Sierra Sue will become the first to complete the double since Trust In A Gust in 2014.

Sierra Sue had been racing well, without winning, until the daughter of Darci Brahma got her confidence back taking out the Mildura Cup (1400m) in July.

The mare came out at her next start to win the Group 2 P B Lawrence Stakes (1400m) at Caulfield then was most unlucky when seventh to Superstorm in the Group 2 Feehan Stakes at The Valley, a run that preceded her victory in the Sir Rupert Clarke.

Young said spring was the time for Sierra Sue to shine and pointed to her win in the Group 2 Rose Of Kingston Stakes at Flemington last year.

While conceding the Mildura Cup gave Sierra Sue confidence again, Young said the stable had tinkered with her work and feed.

“We don’t gallop her over 800 metres any more, we don’t gallop her on the Thursday before the Saturday, so we’ve finally worked her out and she’s a nice happy horse,” Young said.

“We had a little set-back with the stone bruise which may have been a blessing in hindsight as she’s a Group 1 winner now.

“When mares are in form, you keep racing them because when they’re out, they’re hard to get back.”

Young said Sierra Sue had maintained her form since the Sir Rupert Clarke with trips to the beach and will head to the Group 1 Empire Rose Stakes (1600m) at Flemington on October 30.

“She’s flying and comes out of the barn bucking and leaping,” Young said.

“She’s been down the beach a bit and she’s absolutely thriving and it’s a nice three weeks between runs which is a nice progression for her.”