Arguably one of the most improved horse in Australia, September Run has continued her affinity with Flemington to upstage the colts and geldings in the Group One Coolmore Stud Stakes.

Trainer Chris Waller sent September Run to Melbourne after she struggled to measure up against Sydney's best fillies and the three-year-old has proven to be a revelation.

She won consecutive stakes races down the straight at her first two Victorian runs but her crowning glory came on Saturday with a sweeping Group One victory.

Waller says her win is a lesson in perseverance.

"You've just got to keep trying things," Waller said from Rosehill.

"She was just a step below the Sydney fillies in her first up run and I thought, how are we going to get back on the board?

"So we sent her down there and she's created her own legacy. She's a very good straight horse."

Ridden a masterful race by Craig Williams, September Run ($4 fav) tucked in behind the leading pack and edged to the outside to make her run.

Once in clear air, she powered to the line to beat fellow filly Swats That ($7.50) by 1-3/4 lengths with Wild Ruler ($5) best of the colts in third.

Golden Slipper winner Farnan was never in contention and finished tenth with jockey Glen Boss revealing he pulled up lame.

Williams has been aboard September Run for her past three wins and said her turn of foot was her biggest asset.

"She came down from Sydney with B-grade form and just really opened up to the world with some confidence," Williams said.

"This is the best race for three-year-old sprinting in the spring so she had to be good and she was awesome.

"Her acceleration and the sustained speed she can produce. The first time I won on her, she was entitled to get tired at the 100 and all she did was go faster.

"She is a powerhouse. She's gained confidence in three wins and most importantly she has an affinity with the straight."

The win gave Waller his fourth Coolmore Stud Stakes and his first with a filly after previous triumphs with Japonisme (2015), Brazen Beau (2014) and Zoustar (2013).