A dominant win in a race named for the great Sunline has I Am A Star ready for her shot to become the first filly since that champion to win the Doncaster Mile.

Sunline won the first of two Doncasters as a three-year-old in 1999 and I Am A Star's trainer Shane NIchols believes the filly can run a big race on Saturday if she handles the rain-affected conditions.

"If she doesn't get too much of her toe in the ground - if it's firm enough - she'll run out of her skin because that run on Friday night (in the Sunline) topped her off nicely," Nichols said.

"She's improved off that and is just in a good place at the moment."

But Nichols admits it's a significant challenge facing the Group One-winning filly in the Doncaster with 52kg on a track rated heavy on Friday.

"Probably my biggest concern is the fact I've got a three-year-old filly who is a real quality filly but there is a lot of horses close to her in the weights," he said.

"The last filly to win it was Sunline. The freaks are the fillies who win that race. And while she's a great filly, is she a freak?

"She's going to have to be to win.

"She's had a wonderful preparation and she couldn't do anything to disappoint me at this stage, but when you're racing in these big handicaps you certainly need everything in your favour."

I Am A Star arrived in Sydney from Victoria on Friday morning and Nichols said she handled the trip with aplomb.

Her six wins including the Myer Classic have been on good surfaces.

""We wouldn't be happy if it was in a heavy nine or ten range but I think if it got into the soft range, which is looking likely, we're more settled with that position," Nichols said.

"We're not going to get to Good so if we can just get into the soft range we'll be content with that, and definitely run, and she'll run the socks off them,."