The first Group One test in the racing career of Slightly Sweet will double as an examination of her staying prowess after her heart-stopping win in the Keith Nolan Classic at Kembla Grange.

More hopeful than certain Slightly Sweet can also be effective over a middle distance, trainer Jason Coyle will set the filly for the $400,000 Vinery Stakes at Rosehill on March 28, the final day of the Golden Slipper carnival.

"I think you've got to put them through grades over that trip. They will either stay or they won't," Coyle said.

"The Vinery is only two weeks away and it's not a lot of time but it looks the natural progression on what we saw today.

"Since she came in we worked on getting her to a middle distance. On her dam's side it suggests she'll get it but being by (sprinting sire) Charge Forward there's probably a little bit of a question mark."

After settling at the back of Friday's field for Kathy O'Hara, Slightly Sweet ($3.60) tracked the favourite Wine Tales ($2.30) until she was eased to the outside at the 400m mark in the 1600m event.

She quickly made up the advantage held by Wine Tales before gaining control at the 150m and seemed set for a clear-cut victory.

But Wine Tales rallied for Jim Cassidy and it took a photo to declare Slightly Sweet the winner by a short half-head.

Despite the closeness of the finish, O'Hara said the result was never in doubt.

"I know she hasn't won by far but she was definitely always going to win," she said.

Coyle said the best insight Slightly Sweet gave him into her Vinery chances came at the start of the race and not the end.

"It wasn't so much the way she finished it off because the key was she switched off early and you need to do that over 2000 metres," he said.

Slightly Sweet was having only her sixth start in the Group Three race but she had measured up to Sydney's best three-year-olds with recent placings in the Light Fingers Stakes and Surround Stakes.