Debbie Rogerson knows dual Group One winner Costume is worthy of a tilt at Saturday's $A1 million Gr.1 Mackinnon Stakes at Flemington, but isn't sure just how the Savabeel mare will measure up.

Costume flew to Melbourne on Wednesday night and had a light trot and canter at Flemington on Thursday morning.

"She had a good flight over. She travelled well and seems bright,” Rogerson said.

“She did all her fast work at home so she'll just do a bit of light work leading up to the Mackinnon.

"She's drawn nicely in barrier two, but she'll still get back a bit. It's a good field with some really nice horses in there, some that raced in the Cox Plate and Donna Logan's horse Rising Romance that ran second in the Caulfield Cup.

"We know Costume can run good time and she did that both times in her weight-for-age wins in New Zealand, but it's hard to weigh up the form and know just how she'll go. But I am very happy with her."

Both Costume's Group One wins came in 2000m weight-for-age races in the Herbie Dyke Stakes at Te Rapa and the Spring Classic at Hastings, run under the same conditions as the Mackinnon Stakes.

While Rogerson accepts that the Mackinnon is a significant rise in class again, she takes heart that both times she went under two minutes and three seconds to score, times good enough to win four of the last six Mackinnon Stakes, including last year's race won by Side Glance.

As well, the Rogerson stable has historic success in the Mackinnon with Rogerson's training partner and husband Graeme producing Ebony Grosve to win in 1997 and La Bella Dama to win in 2001.

"We hope we are good enough," Rogerson said.

Costume is rated an $81 outsider with some bookmakers in Australia, in a market headed by Rising Romance at $5.

Rogerson said Costume would return to New Zealand on Wednesday to prepare for the final start of her career, in the Gr.1 Zabeel Classic (2000m) at Ellerslie on Boxing Day.

Bred and raced by Waikato Stud, Costume is in foal to Pins.