In-form mare Sedanzer has enhanced her reputation as a black-type winner-in-waiting by staying unbeaten this preparation at Rosehill.

The four-year-old mare racked up her fifth career win from 11 starts with a 1-1/2 length victory in the Boxing Day at Royal Randwick Handicap (1500m) on Saturday.

"There are bigger and better things to come. She's certainly a mare that will be winning black type in the very near future," co-trainer Gai Waterhouse said.

Waterhouse was coy about Sedanzer's next step towards that goal, though the Group Three Belle Of The Turf (1600m) at Gosford on December 28 was an option.

"She's enjoying going through her classes and I can't see why she couldn't go further," she said.

In-form apprentice Rachel King, who earlier rode Perfect Pitch to her first victory, has no doubt $2.50 favourite Sedanzer is capable of going up in class.

"She was very impressive first-up and she was even better again today. She's proving she's a really classy filly on the up," King said.

"She won very easy. She eased down in the last couple of strides. It's going to be really exciting to see what she can do in this preparation."

Hunter Jack ($21) took second a neck clear of Cellarman ($12).

King said Sedanzer did not run to the usual racing pattern employed by Waterhouse and Adrian Bott.

"She is not a typical Gai horse. She doesn't jump and run," King said.

"We ride her quietly early, sit on her and let her settle. If we do that she can produce a very good turn of foot - she hits the line strongly."