One of the major questions heading into Saturday's rich Inglis Classic is whether speedy filly Diamond Earth will stretch her brilliance to 1200 metres.Her jockey Peter Robl believes the step up in distance is the only query to the Anthony Cummings-trained filly adding the $250,000 event at Rosehill to her two previous Inglis race victories."She's flying," Robl said of the last-start Inglis Nursery winner."I worked her on Tuesday morning and I think the only thing that will beat her is her."If s

One of the major questions heading into Saturday's rich Inglis Classic is whether speedy filly Diamond Earth will stretch her brilliance to 1200 metres.

Her jockey Peter Robl believes the step up in distance is the only query to the Anthony Cummings-trained filly adding the $250,000 event at Rosehill to her two previous Inglis race victories.

"She's flying," Robl said of the last-start Inglis Nursery winner.

"I worked her on Tuesday morning and I think the only thing that will beat her is her.

"If she relaxes and gets the six furlongs (1200m), they won't beat her."

Diamond Earth was ridden for pure speed last time out at Warwick Farm when she showed her rivals a clean pair of heels and held off subsequent city winner De Shamekh by three-quarters of a length over the 1000m.

Her Inglis Nursery success added to her victory at Moonee Valley on Cox Plate day in the Inglis Banner (1000m).

Another win on Saturday would take the filly's prize money to more than $475,000 in just four starts.

While Diamond Earth has the form on the board it's one of the unraced brigade, Cavalry Rose, who has drawn the attention of punters in early betting.

The Gai Waterhouse-trained Snippetsboy is the $2.90 favourite to make a winning debut while the Gerald Ryan-trained Cavalry Rose is at $3.20 and Diamond Earth $3.60.

"Cavalry Rose has been $3.50 in to $3.20, it hasn't been huge money but all of the money has been for her," Matt Jenkins from TAB Sportsbet said.

"There's been no money for Gai's runner, or even Diamond Earth yet which is a little bit surprising given you know what you are getting with Diamond Earth having won her past two."

Diamond Earth will be out to repeat the feats of Chance Bye from 2010 and Pane In The Glass last year who both claimed the Inglis Classic after winning the Inglis Nursery.

Chance Bye went on to win the Silver Slipper and book a Golden Slipper berth while Pane In The Glass placed in four Group races in her two-year-old season including the Group One Sires' Produce Stakes and Champagne Stakes.

Robl believes Diamond Earth also has the potential to progress to some autumn features.

"If she proves on Saturday she can run a good 1200 metres, I think she might be up to the good two-year-old fillies races," he said.

The Inglis Classic is restricted to horses offered for sale at last year's Inglis Classic Sale.