Increased prizemoney to $275,000, its elevation to group 3 status and the fact the Slipper is now just two weeks after the March 8 showpiece makes it more attractive to racing heavyweights.

Sweeney is no certainty to secure a Black Opal ride and hopes a local can rise to the challenge and upstage the interstate runners.

He said interest from outside the ACT's border will increase the race's quality and prestige, in the same vein the European invaders have boosted the Melbourne Cup.

"For a local horse to win it, I think those days are just about gone," he said. "It's going to be like 10 years ago when it was tailor made for interstaters, we just have to take it on the chin.

"The race is going to be very strong, the timing is the best it's ever been and it's great for the public to see the top jockeys and horses go around."

Paul Jones and Barbara Joseph hope maiden runner Darts Away may squeeze into the Black Opal field, while Wagga Guineas winner Just A Blur is their best hope in the $120,000 listed Canberra Guineas.

Jones agreed the challenge was far greater for local trainers to win, but not impossible.

"It's definitely a lot harder, but we've proven over the last few years we can get a winner here or there," Jones said.

"The good horses do come for the Black Opal and Canberra Cup. [Leading Sydney trainer] Chris Waller has a stable of runners lined up, the Canberra Cup is worth $200,000 and I don't think there's a race like that in Sydney that weekend."

Canberra trainer Nick Olive's filly Single Gaze is primed for the Black Opal after finishing third at last month's rich Magic Millions and a solid barrier trial at Thoroughbred Park last weekend.

"I couldn't be happier with her, she came through the trial terrific and I think she's a bit stronger than she was on the Gold Coast," Olive said.

"We'll see how the Black Opal goes, I'm not even thinking about [whether to nominate for] the Golden Slipper, to be honest."

He is adamant the race has a strong case to be upgraded to group 2 given the rapid increase in its stature.

"I think it could easily in time, it is that quality of race," he said. "The [Canberra] Guineas is growing in stature and so is the national sprint, I know there's a certain procedure for these things to get upgraded, but the carnival's getting stronger and stronger.

"You've got your main Slipper hopes having their last hitout, it could be one of the strongest Black Opal fields we've had in years."

Canberra trainer Matthew Dale's Canberra Guineas hope Rom Baro has been installed a $4.50 favourite for April's inaugural Country Championships final at Randwick.

Rom Baro is one of five horses near the top of betting for the $300,000 race, including Fell Swoop ($7), American Time ($7), Royal Jackpot ($8) and Waco Kid ($11).