Peter Snowden has won three Blue Diamond Stakes and the trainer expects the Preludes at Caulfield to provide a pointer to his chances of a fourth.

Snowden and his son Paul have impressive Randwick debut winner Rulership set to clash with the Anthony Freedman-trained Blue Diamond favourite Hanseatic in Saturday's Prelude (1100m) for colts and geldings.

While unbeaten Hanseatic was dominant in the Preview at Caulfield on January 25 at his second start, Rulership impressed on debut at Randwick the same day with a 2-1/4-length win and is second favourite for the Blue Diamond.

"This will be his first start at Caulfield which is never easy but he was pretty impressive in his only start and his trials had been pretty good leading into it," Snowden said.

"The favourite for the Diamond is in there so we'll see how he measures up against him on Saturday.

"Rulership is well above average. The only thing he lacks is a bit of race experience that way, so if he gets close to Hanseatic on Saturday you'd dare to think he would improve a bit off that in a fortnight."

Snowden won the Group One Blue Diamond with Sepoy (2011) and Earthquake (2014) when head trainer for Darley and added another in partnership with Paul with Pride Of Dubai in 2015.

He said Rulership looked to be the stable's leading Diamond contender but he was keen to see what Fresh did in Saturday's fillies Prelude before deciding whether she pressed on.

Fresh won on debut at Geelong then finished second to A Beautiful Night in the fillies Preview after a less-than-ideal run from a wide draw.

"This will be her third run so I don't believe in going too far in their first preparation," he said.

"I'm not worried about her condition-wise. It's just how she is mentally before and after the race that will tell me whether she needs to go one more or Saturday will be enough.

"I certainly wouldn't rule out going to the Diamond, but we'll know more after Saturday."

Fresh is one of the leading contenders for the fillies Prelude and will be joined by stablemate Diamondesque who won on debut at The Valley in December.

Snowden believes Diamondesque is blessed with natural ability but will improve on whatever she does on Saturday.

"If she's competitive she could bounce on and go to the Diamond," he said.

Barbaric was kept in Sydney after drawing wide at Caulfield and he could clinch a Diamond start if he performs strongly in Saturday's Lonhro Plate at Warwick Farm.