The Clan O'Sullivan offers a free pass through to Canberra's signature event, the Black Opal Stakes, but it is another juvenile feature that Paul Snowden has in mind for his runner in the $50,000 race.

King Of Roseau is on trial for a start in the $2 million Group 1 Blue Diamond Stakes when he makes his debut on Friday.

"He's a smart horse, we don't know where his roof is," Snowden said.

"He was qualified for the juvenile race and could have targeted the Magic Millions but we just thought he wasn't ready for that kind of pressure.

"This looks like the perfect race for him and he could end up anywhere. He could be a Blue Diamond horse."

King Of Roseau, a son of Capitalist who is out of a daughter of Coolmore Classic winner and Doncaster Mile placegetter Danni Martine, cost $95,000 at this year's Magic Millions Yearling Sale.

He had one trial at Randwick in September, finishing second, the same position he finished in a Rosehill trial on December 5 before a win in a 900m trial at the same track on December 18.

King Of Roseau, who will be ridden by Tommy Sherry, has drawn barrier five in the field of nine, which also includes the slick Gai Waterhouse and Adrian Bott-trained Stress Boss filly Madrina.

"He's found the front in all of his trials, so he'll butter up in the front two or three but (Tom) Sherry knows the horse very well so will make that decision if something wants to go too fast."