The Kris Lees-trained filly Invincible Gem made giant strides last season, rising from a maiden at Canterbury to winning the Group III Spring Stakes at Randwick and finishing second in the Group I Randwick Guineas.
The daughter of I Am Invincible showed she had not gone backwards in the meantime when downing her triple Group I winning stablemate Le Romain in Saturday's $200,000 Group II ATC Missile Stakes at Randwick.
Settled back towards the rear of the field by Corey Brown as Jungle Edge and Memes cut out the early running, Invincible Gem (images Steve Hart) was dragged into the race by her stablemate Le Romain before coming clear to win by one and a quarter lengths from $2million earner Le Romain.
"She's come back in super order," Lees said.
"She's been doing all the work with him (Le Romain). He's probably worked a little better than her at home but she is a high-quality mare.
"You never know how they will come back in the early spring and she has come back in terrific order.
"Last preparation she kept surprising me. I was looking to spell her but she'd do so well after a win I kept raising the bar and she handled every step.
"Another advertisement for that stallion (I Am Invincible), he just improves mares incredibly well."
Retained to race by her breeders, Invincible Gem is the second winner from Diamond Day, a minor winner by Marwina, whose family is barren of Black Type for five generations.
She has put together an imposing record with five wins and three placings from 10 starts with prizemoney of $544,850.
Lees said the Group II ATC Golden Pendant (1400m) on September 23 at Rosehill remains Invincible Gem's initial target of the preparation before a potential trip to Melbourne for the Group I VRC Myer Classic (1600m).
Invincible Gem is one of 21 stakes-winners by I Am Invincible, who was the leading Australian Sire of 2016/ 2017 by wins posting one more than Snitzel.
He is fully booked this spring at a fee of $110,000.