Of the many two-year-olds that have arrived in his stable this season, perhaps Metastasio has surprised trainer Peter Snowden the most.

An impressive debut winner at Flemington on Saturday, Metastasio was promptly inserted high in markets for the Blue Diamond Stakes on February 23 but she will have to earn her way to the $1 million race.

Metastasio is not among the nominations for Melbourne's richest juvenile event and has a pedigree to suggest she should struggle against the early comers.

"She looks a precocious type and lived up to what we had seen her do in her work," Snowden said.

"But when you look at her pedigree there's no way she should be doing what she's doing.

"She's not in the Blue Diamond yet. She will run in the Prelude and that will decide whether we pay the $55,000 late entry fee."

Metastasio is by her owner Sheikh Mohammed's stallion Street Cry out of Singspiel mare Librettist.

A Dubai World Cup winner, Street Cry is the sire of 2009 Melbourne Cup winner Shocking and champion United States mare Zenyatta.

Singspiel won the Japan Cup (2400m) and the World Cup (2000m) while Librettist was a dual Group One winner over a mile in France.

The TAB has Metastasio on the second line of betting alongside Crack A Roadie at $13 with Miracles Of Life heading the market at $7.

Like Metastasio, Miracles Of Life is not entered for the Blue Diamond but after winning her two starts in Adelaide by a combined 14-1/2 lengths, she will be given her chance to cement a place via the Fillies Preview next Saturday.

Marseille Roulette, winner of Saturday's Inglis Classic at Rosehill, is among the original Blue Diamond nominations and trainer Gai Waterhouse will monitor his progress over the coming weeks.

"He'll go to Melbourne for the Prelude or the Blue Diamond," she said.

Marseille Roulette is by Zizou who won the Maribyrnong Trial on debut in October 2006.

Although he didn't win another race during his career with David Hayes, Zizou's five seconds include the 2007 Blue Diamond and Golden Slipper.

Marseille Roulette, a winner for first time owner Tomohiro Sekiguchi, is a $35 chance in the Blue Diamond.