Fangirl has raced twice at Flemington previously.
As a three-year-old filly, Fangirl showed a devastating turn of foot to win the 2021 Group 3 Carbine Club Stakes (1600m), while her only other run at Flemington was when she was fourth to Pride Of Jenni in last year's Champions Mile.
Fangirl is a three-time Group 1 winner, her most recent being over Mr Brightside, also an opponent on Saturday, in last year's King Charles III.
Waller is expecting Fangirl to bounce back on Saturday.
"Fangirl is coming off a defeat in Sydney that we didn't expect but there's been no signs to suggest she can't bounce back," Waller said.
"She's undergone proper veterinary checks and she's well.
"She's a talented horse, she's beaten the best of them.
"We just need to see her get back to her best form and there's no reason she can't."