The Blue Diamond Stakes picture will become clearer after Saturday's Preludes at Caulfield with Sheikh Mohammed's Darley operation looking to have four runners in the $1 million finale.

But two of those - Metastasio and Montsegur were not among the original Blue Diamond nominations - leaving Darley liable for a $110,000 pay-up to run them.

Metastasio was elevated to second favouritism following her comprehensive win in Saturday's Chairman's Stakes, leapfrogging stablemate Guelph, a winner at Warwick Farm a week earlier.

Montsegur won her debut on Boxing Day before finishing sixth behind Adelaide speedster Miracles Of Life who was also not declared for the race early.

Dissident, winner of the colts and geldings Preview last Saturday week, brings to four the number of leading contenders not among the original entries, generating a potential $220,000 for the Melbourne Racing Club to help offset the purse.

While Metastasio has impressed bookmakers, trainer Peter Snowden remains loyal to his opinion of Guelph who he rates the better of the two.

Her Warwick Farm win came after she got much further back than anticipated and he was impressed with her finishing sprint.

"She is a lovely big filly," Snowden said.

"She will have to be closer in a Blue Diamond but she has shown a lot."

Guelph is by Darley stallion Elusive Quality out of 2007 Blue Diamond Prelude winner Camarilla who finished an unlucky fourth in the big race then subsequently won the AJC Sires' Produce Stakes.

Miracles Of Life dominates the Blue Diamond market at $2.80 following her dominant win in the Fillies Preview and she will not start again before the race on February 23.

Metastasio is at $6.50 with Guelph at $7.50.

Darley will be represented by Kuroshio in the colts and geldings Prelude on Saturday.

Kuroshio was run down late by Dissident in the Preview and is a $21 Blue Diamond chance.