Champion Sydney apprentice Winona Costin and trainer Mike Van Gestel have celebrated their first Group wins with Casino Dancer in an Angst Stakes upset.

Rejected by punters, Casino Dancer was a $51 chance in Saturday's Group Three mile with proven performer Peeping the $4.20 favourite.

Costin settled Casino Dancer better than midfield and she came out of the pack to put a widening two lengths on Wine Tales ($6).

"She needs a bit of luck this mare and she's got enormous ability but we could never get it out of her," Van Gestel said.

"We put blinkers on and they have really helped. She took the gaps.

"This is my first Group Three win. I've had a second and a third and finally this win."

The win may or may not have decided Casino Dancer's future.

"She might go to stud," Van Gestel said.

"We had her booked to Deep Field but she needed to be a stakes winner to go to him so we kept racing.

"Now she's a Group Three winner so we don't know."

Costin said it was good to get a Group win on her resume.

"I've had a Listed winner before but this is my first Group win," she said.

Peeping's jockey Sam Clipperton said the distance and the firm track might have played a part in her failure to run on from eighth.