Country filly Martini Mumma has taken another step up at Rosehill with a convincing win in a Highway Handicap.

Goulburn trainer Matthew Dale has set his sights on a stakes race at next month's Scone Cup carnival with Martini Mumma after the promising filly stepped up in a Highway Handicap at Rosehill to continue her unbeaten preparation.

Dale was keen to test Martini Mumma in Saturday's Highway over 1100m after the grey filly put together two-straight wins by big margins in a Wagga Wagga Maiden and a Goulburn benchmark-58, respectively, in her first two starts this campaign.

Martini Mumma answered the challenge in style to win Saturday's Highway for country-trained horses by 2-1/2 lengths, taking her overall record to three wins from four starts.

After seeing the filly's Rosehill performance, Dale is happy to press on with the next part of his plan to give Martini Mumma her opportunity in the Listed Denise's Joy Stakes (1100m) for three-year-old fillies on May 18.

"I'm pretty rapt with her and she'll earn a crack now at Scone in the Denise's Joy," Dale said.

"I knew we were jumping a few levels today and I thought if she could do it, and she's done it really well there, she definitely deserves a crack at it."

Dale said Martini Mumma has been an "extremely raw" filly and had taken quite a bit of management because of her hard-going nature on the track.

But the trainer is thrilled with the development Martini Mumma is making and he was taken by her improved race craft again on Saturday when she was able to settle in behind the speed under apprentice Dylan Gibbons before sprinting to the front at the 200m.

"That was really impressive there today," Dale said.

"That was as strong a Highway as I've contested."

Martini Mumma ($4.20) defeated Tanglewood ($6.50) with Wilbury ($18) another 1-1/4-lengths away third.

"Coming up today I thought she may be a little bit raw and it might come a bit quick for her," Dale said.

"But when I saw her in the parade and again behind the barriers, she handled it beautifully.

"She's really come on."