Winx has sealed her reputation as Australia's best racehorse while earning the ultimate accolade from her trainer in winning the $3 million Doncaster Mile.

"I'll call her a champion while I can speak," trainer Chris Waller.

"I thought she was beaten at the half-mile. She must have an amazing will to win."

Sent out of the shortest-priced favourites in Doncaster history, Winx ($1.80) had to overcome a reluctance to stretch out on a soft track to make in nine successive wins at Randwick on Saturday.

She settled well back in the field, forcing Hugh Bowman to navigate a ground-saving but risky passage to have Winx within striking distance at the 300m.

Once there was clear galloping room in front of her, Winx sprinted to the front before holding Happy Clapper ($13) and Azkadellia ($9) at bay.

Matching the dominance Black Caviar enjoyed over her rivals, Winx has won five Group One races this season, including the Cox Plate.

Fittingly, she returned to scale to a reception not seen at Randwick since Black Caviar won the 2013 TJ Smith Stakes in what turned out to be the last of her unbeaten 25 starts.

Bowman described Winx as his once-in-a-lifetime horse.

"It's an absolute honour to be involved with her," he said.

He said Winx didn't like the going on offer.

"She wasn't overly comfortable in it," he said.

"So the fact that she wasn't comfortable and could still produce that finish is something only a horse of champion qualities can do."