Jockey Nikita Beriman is progressing well in her quest to ride Dubious at 48kg in a bid for history at Eagle Farm on Saturday.

Beriman already has a strict regime of workouts and diets which have her riding in peak form this season.

"I am walking around at 50kg so the rest should be no worry," she said.

"My last Group One was for Ciaron 12 years ago so here is hoping for a repeat."

Beriman was only 21 when she won the Group One Emirates on Tears I Cry in 2007.

Dubious can become the first two-year-old in 61 years to win an open Group One race in Brisbane if he takes the Kingsford Smith Cup (1300m).

Until the 1970s it was not uncommon for two-year-olds to oppose older horses in Brisbane feature races for the simple reason the carnival was near the end of the season.

However, since the major sprints in Brisbane are now weight-for-age and not handicaps it is rare for two-year-olds to tackle Group One open races.

Wiggle was the last to win when became the sixth two-year-old to take the Stradbroke Handicap in 1958.

The Kingsford Smith has a long and convoluted history, originally being a Quality named the JT Delaney when first run in 1964 at Doomben as a major lead-up to the Stradbroke.