Justaboom has stamped her Black Type credentials with a win at Caulfield.
The daughter of Justify could return to Caulfield in three weeks to contest the Group 2 Autumn Classic over the same trip she scored over in the IVE> Handicap (1800m) on Saturday.
Ridden by Jamie Mott, Justaboom ($6) defeated Our Couver ($10) by a length with Dunbelievin' ($7.50) close-up in third position.
Justaboom entered Saturday's race off a maiden win at Pakenham and de Kock said the stable has always held the filly in high esteem.
"She's a nice, smart young filly and Justify is turning out to be a fantastic stallion," de Kock said.
"Most of the crew (owners) are back home (South Africa) and it's the early hours there, so I don't know if they'll be awake watching this, so they'll have something to look forward to when they do.
"We think she's a Black Type filly, but we just wanted to see her get through today's race.
"We've seen her get through it very well, so I think we'll just start out on a nice Black Type program from here."
De Kock said all the filly's races over a distance and at Black Type would come into consideration for Justaboom, although he believes 2000m will possibly see her out.
"I reckon 10 furlongs (2000m) is about where she is at," de Kock said.
"There's an 1800-metre race back here in three weeks against the boys, so she may go there, but there's not much around, so we'll have to look around.
"She's fit and well, so it's hard to stop her."
Mott, who has ridden the filly in all four starts to date, said Justaboom was still learning what racing was about.
"She's still an inexperienced horse and not sure on how to put a race away as yet, but she is building a nice record," Mott said.
"I think she's looking for further. The way she paraded today, a hot day, the way she pulled-up after the race, she wouldn't blow a candle out.
"She had a look around. She came back in quiet and relaxed.
"She's a horse that is not finished for the preparation."