Melbourne trainer John Sadler and champion jockey Glen Boss had mixed fortunes in their raid on Perth racing at Ascot on Saturday.

Scarletini had no luck in the WA Oaks, finishing fourth after being unable to get a clear run in the straight but two-year-old filly Ms Funovits turned brightened the day with her Karrakatta Plate win.

Ms Funovits became the first interstate horse to win the Group Two race in 23 years and gave her supporters little cause for concern.

Boss quickly got her across from barrier 13 to camp outside the leader, Camporella.

Ms Funovits ($4.40 fav) had plenty of reserves and beat Trichologist by a length-and-a-half with Camporella holding third.

"She's a really good filly. We didn't bring her over her thinking we were just a chance," Sadler told Perth Racing.

"Bossy is one of the all-time-great big race riders."

The win was also a boost for owner Phil Sly who has been battling cancer for the past couple of years.

Sly travelled from Melbourne to Perth just a week after having half of a lung removed.

"He had no intention of coming over until everyone told him he couldn't, and you never tell Phil Sly he can't do something," Sadler said.

Victorian colt Umatilla won the 1990 Karrakatta Plate when it was a Group One race run in the summer.

Boss opted to go to Perth rather than try to get rides at Saturday's Golden Slipper meeting in Sydney and picked up the Listed Melvista Stakes (2200m) aboard the Dan Morton-trained Gold Broker.